I treat annulment risk as very small and forecast the numeric outcome conditional on a normal July 2026 publication. The Economist says the Big Mac data are updated 1-2 times per year, typically in January and July, and the January 2026 ranking includes all ten named countries, so the resolution pool is almost certainly non-empty if the July edition appears. (globalinflation.org)

The January 2026 raw % under/over-valued starting points are: Argentina -9.6, Brazil -27.3, Chile -11.4, Colombia +1.5, Egypt -56.7, India -59.0, Indonesia -58.8, Mexico +0.8, South Africa -45.1, and Turkey -3.6, with the US Big Mac baseline at $6.12. These are the exact countries and January levels that matter for the question. (globalinflation.org)

The historical base rate for the largest Jan-to-Jul move among these countries is usually in the high single digits to high teens, but with a fat right tail. Using the recent half-year records visible on the country history pages, I get a max of roughly 9 pp in 2021, 15 pp in 2022, 17 pp in 2023, and 48 pp in 2024, the last one driven by Argentina moving from about -33% in January 2024 to about +15% in July 2024. Turkey has repeatedly posted 11-15 pp Jan-to-Jul swings, Mexico reached about 17 pp in 2023, and Brazil reached about 11 pp in 2024. That history argues for a distribution centered well above 10 pp, but with a meaningful low-probability tail into the 30s and 40s. (globalinflation.org)

As of early May 2026, spot FX already points to some re-ranking pressure relative to the January Economist snapshot. USD/ARS is about 1401 versus 1445.76 in the January Big Mac data; USD/BRL about 4.8957 versus 5.37; USD/CLP about 891.85 versus 883.85; USD/COP about 3784.74 versus 3686.73; USD/EGP about 52.72 versus 47.24; USD/INR about 95.146 versus 90.30; USD/IDR about 17395.5 versus 16885; USD/MXN about 17.1722 versus 17.68; USD/ZAR about 16.3682 versus 16.35; and USD/TRY about 45.3757 versus 43.19. Mechanically, if local burger prices were frozen, Brazil would move noticeably closer to fair value, Mexico would become somewhat more overvalued, while Turkey, Egypt, India and Indonesia would become somewhat more undervalued. (investing.com)

But local-price inflation matters a lot, especially for Argentina and Turkey. Argentina’s page shows 31.5% y/y inflation at December 2025, with IMF 2026 year-end inflation at 16.4%; Turkey shows 30.65% y/y at January 2026, with IMF 2026 year-end inflation at 24.7%. Egypt is also still elevated at 20.4% y/y at December 2025. By contrast, Brazil, Chile, Colombia, India, Indonesia, Mexico and South Africa are mostly in low-to-mid single digits or low double digits, which makes very large burger-price jumps there less likely over just one half-year. (globalinflation.org)

My modal scenario is therefore: Argentina posts another meaningful menu-price increase but not a 2024-style discontinuity; Brazil and Mexico keep most of their currency strength into July; Turkey’s lira weakens further but menu-price inflation offsets a lot of that; Egypt stays high-inflation but with partial pass-through; the remaining countries stay fairly stable. Using simple PPP arithmetic, an illustrative July path such as Argentina at 9200 ARS and 1480 ARS/USD gives about +1.08% raw overvaluation, Brazil at 24.3 BRL and 4.95 BRL/USD gives about -20.18%, Turkey at 290 TRY and 46.8 TRY/USD gives about +0.76%, and Mexico at 112 MXN and 17.35 MXN/USD gives about +4.96%. Relative to January, those example paths correspond to changes of about 10.7 pp for Argentina, 7.1 pp for Brazil, 4.4 pp for Turkey, and 4.2 pp for Mexico. That is why I think Argentina is the single most likely winner, with Brazil the cleanest alternative and Turkey the main upside-tail alternative if exchange-rate slippage outpaces menu repricing. (globalinflation.org)

My final median forecast for the resolved largest absolute change is 13.6 percentage points. I put about 22% probability on a result below 10 pp, about 16% above 20 pp, about 3.2% above 30 pp, and about 0.5% above 40 pp. In words: the most likely outcome is a low-teens max move, but the distribution should keep a meaningful right tail because Argentina has recently demonstrated that very large half-year swings are possible, even if current conditions look more orderly than the 2024 shock year. (globalinflation.org)

I model this as a six-month max-over-countries problem. The Economist’s raw Big Mac index compares each country’s Big Mac price converted at the market exchange rate with the US price; the Economist’s public repo documents that the raw USD index is built from local price, dollar exchange rate, and dollar price fields. For January 2026, two independent reproductions of the Economist table agree on the ten starting raw readings relevant here: Argentina -9.6%, Brazil -27.3%, Chile -11.4%, Colombia +1.5%, Egypt -56.8%, India -58.9%, Indonesia -58.9%, Mexico +0.8%, South Africa -45.1%, and Turkey -3.5%. The Economist’s GitHub releases page still shows January 2025 as its latest packaged public release, so I treated the January 2026 values as cross-checked secondary pulls rather than a directly downloadable official file. (github.com)

For base rates, I reconstructed recent January-to-July moves from country history pages that explicitly attribute their Big Mac records to The Economist. Across these ten countries, the largest Jan→Jul change was usually in the mid-to-high teens or low 20s, with notable spikes around the high 20s and one major outlier in 2024 when Argentina jumped from about -33% in January to about +15% in July. That history tells me the right center is not 10-12 pp; it is closer to the high teens, with a real but minority tail into the 30s. (globalinflation.org)

The most plausible 2026 winners are Mexico, Argentina, and Turkey, with Colombia and Brazil as secondary contenders. Mexico and Colombia start near parity (+0.8% and +1.5%), and Turkey starts only slightly undervalued (-3.5%). Because the raw index is just the percentage gap between a country’s dollar Big Mac price and the US dollar price, a roughly 10-15% relative FX move that is not fully offset by local burger-price resets can translate into a roughly similar double-digit percentage-point move in the raw misvaluation reading; that is an inference from the published formula. (github.com)

Current macro conditions keep the tail alive but do not scream repeat-of-2024. Reuters reported on April 22, 2026 that Turkey’s central bank held its key rate at 37%, had halted its easing cycle, and was managing spillovers from war-related energy shocks while analysts expected it to stay tight into the summer; globalinflation lists Turkey’s latest annual inflation at 30.6%. Argentina still has 31.5% inflation and a 32% April 2026 policy rate, but Reuters also reported IMF-backed progress, stronger reserve accumulation, and over $5.5bn of central-bank FX purchases in 2026, which makes another immediate disorderly Argentina-style jump less likely than it looked a year earlier. Egypt remains a tail-risk devaluation case, but the IMF says the country has maintained a flexible exchange-rate regime and that headline inflation fell to 11.9% in January 2026, which lowers the chance of another abrupt step-change before July. (marketscreener.com)

The rest of the field looks more stable. Globalinflation lists Mexico at 3.9% inflation with a 10.0% April 2026 policy rate, Colombia at 5.6% and 9.5%, Brazil at 5.2% and 13.75%, and South Africa at 3.4% and 7.5%. Those settings can still produce single-digit or low-teens raw-index moves, but on current information they look less likely than Mexico/Turkey/Argentina to produce the single largest shock. India and Indonesia, meanwhile, have been among the steadiest names in the historical panel. (globalinflation.org)

I am effectively conditioning on publication/non-annulment; the index is normally updated twice yearly and all ten countries are present in the January 2026 table, so I treat annulment risk as small relative to the numeric uncertainty in the largest move. Putting everything together, my median forecast is 19.0 percentage points. I put about 50% probability on 13-24 pp, about 80% on 11-30 pp, and only a small tail above 40 pp. (mappr.co)

I treated the resolution value as the maximum absolute percentage-point change in the raw USD over/undervaluation measure across the ten listed countries. The Economist’s official Big Mac data repository says the raw series is stored in big-mac-raw-index.csv and that USD_raw is the raw index relative to the US dollar. An accessible Jan 2026 mirror of that dataset gives the relevant starting values as Argentina -9.6%, Brazil -27.0%, Chile -11.4%, Colombia +1.5%, Egypt -56.7%, India -59.0%, Indonesia -58.8%, Mexico +0.8%, South Africa -45.1%, and Turkey -3.6%. (github.com)

For base rates, I looked at past January-to-July moves for the same countries. The big historical half-year swings in this set include Argentina from about -33% to +15% in 2024, a 48 pp move; Brazil from about 0% to -19% in 2020, a 19 pp move; Mexico from about -22% to -5% in 2023, a 17 pp move; Turkey from about -63% to -48% in 2022, a 15 pp move; and Egypt from about -66% to -53% in 2023, a 13 pp move. By contrast, India and Indonesia usually move only around 0-5 pp over a half-year, and Chile and South Africa are often low-single-digit movers. So the historical maximum is usually generated by one of Argentina, Turkey, Mexico, Brazil, or Egypt, with a fat right tail from occasional regime shifts or large repricings. (globalinflation.org)

The raw index is mainly a function of local Big Mac price, the FX rate, and the US Big Mac price. Using January local prices together with early-May FX as a nowcast, before any July burger-price reset, would already move several countries materially. Since January, USD/BRL moved from 5.37 to about 4.93, USD/EGP from 47.24 to just above 53.5, USD/TRY from 43.19 to about 45.2, USD/ARS from 1445.76 to about 1389.6, and USD/MXN from 17.68 to about 17.26. My calculation from those FX moves and the January burger prices is that Brazil would already be roughly 6 pp less undervalued than in January, Egypt roughly 5 pp more undervalued, Turkey roughly 4 pp more undervalued, Argentina roughly 4 pp less undervalued, and Mexico roughly 2-3 pp more overvalued if local burger prices had not changed. (globalinflation.org)

But burger prices are not static, and that is why Turkey and Argentina stand out. Turkey’s local Big Mac price has tended to jump sharply between January and July in recent years, including 75 to 95 in 2023 and 120 to 155 in 2024, and it was already up from 190 in Jan 2025 to 255 in Jan 2026. Argentina has also had very large mid-year repricings, including 980 to 1650 in 2023 and 3150 to 6100 in 2024. Egypt has shown similar but somewhat less consistent jumps, such as 55 to 81 in 2023 and 85 to 120 in 2024. By contrast, Brazil’s Big Mac price sat at 23.90 BRL in Jan 2024, Jul 2024, Jan 2025, and Jan 2026, while Mexico was 95 MXN in both Jan and Jul 2024. That makes Turkey and Argentina the most natural leaders for the max-change question, with Egypt a secondary tail risk and Brazil or Mexico more dependent on FX alone. (globalinflation.org)

The macro backdrop reinforces that ranking. Turkey’s central bank said in February that inflation was projected between 15% and 21% for end-2026 and that tight monetary policy would be maintained; at the same time, the lira was at a fresh record low above 45 per dollar in early May and Turkey’s April inflation was above 32%, which keeps meaningful repricing pressure alive. Egypt’s pound weakened to just above 53 per dollar in early May after weeks of volatility, while April urban inflation slowed to 14.9%; that combination suggests some burger-price catch-up may offset part of the FX move by July. Mexico looks less explosive: Banxico cut to 6.50% on May 7 and signaled a hold, while BBVA described the peso as behaving more like other EM currencies, so Mexico is still live but looks less likely than Turkey or Argentina to generate the single biggest swing over one edition. (tcmb.gov.tr)

Putting those pieces together, my modal path is that the winning country is Turkey or Argentina and the final maximum lands in the low-to-mid teens. I keep meaningful probability on a quieter result below 10 pp if Turkey’s and Argentina’s local prices do not reset much before July, but I also keep a nontrivial right tail into the 20s because the historical record for these countries includes abrupt repricings and large half-year jumps. My median forecast is 13.8 percentage points. In the CDF, that corresponds to about a 24% chance the answer is below 10 pp, about a 52% chance it is below 14 pp, about an 86% chance it is below 20 pp, and about a 98% chance it is below 30 pp. (globalinflation.org)

I am treating this as a conditional forecast on a numeric resolution: a July 2026 Big Mac Index edition is published and at least one of the ten countries appears in both editions. A July 2025 edition did exist, so publication risk does not look like the main driver here. My median forecast for the largest absolute January-to-July 2026 raw move is about 12 percentage points, with a mean around 14 pp. Argentina is my single most likely winner; Brazil, Turkey, and Egypt are the main alternatives. (elledgy-magazine.com)

The January 2026 raw starting points in the target basket ranged from Colombia at +1.5% and Mexico at +0.8% to Egypt at -56.7%, India at -59.0%, and Indonesia at -58.8%. Using the historical country tables that reproduce Economist data, and recomputing raw undervaluation directly from dollar burger prices divided by the U.S. burger price, the biggest January-to-July move in this basket was about 17.3 pp in 2023 (Mexico), while 2024 produced a much larger outlier of about 47.8 pp (Argentina). That tells me the base rate for a normal year is low-teens, but Argentina can create a very fat right tail when policy or pricing shifts are abrupt. (globalinflation.org)

I expect the U.S. Big Mac price to matter only modestly. The U.S. price was $6.12 in January 2026; it was unchanged at $5.69 between January and July 2024, and it rose from $5.79 in January 2025 to $6.01 in July 2025. So my central assumption is only a small U.S. increase by July 2026, meaning that exchange-rate moves and local burger repricing in the ten-country basket should dominate the resolution. (globalinflation.org)

Argentina is the clearest upside-risk country. In the January 2026 data, a Big Mac cost 8,000 ARS, the FX rate used was 1,445.76 ARS per dollar, and the raw valuation was about -9.6%. By early May, USD/ARS was running around 1,395, materially stronger for the peso than the January snapshot, and Reuters reported the peso staying firm in April even while inflation over the year-to-date was still well above FX depreciation. IMF staff also said Argentina had refined its FX framework and was rebuilding reserve buffers, while the central-bank survey tracked by Reuters showed analysts raising 2026 inflation expectations. Put together, that makes a swing back toward fair value or mild overvaluation plausible if local burger prices keep rising faster than the peso weakens. I think Argentina alone has a meaningful chance of producing a 10-20 pp move, and a small but real chance of another outsized jump. (globalinflation.org)

Turkey is the next-biggest nonlinear candidate, but I think the tail is smaller than Argentina’s. Turkey entered January 2026 at about -3.6% raw undervaluation, with a 255 TRY Big Mac and 43.19 TRY per dollar in the index. By May 8, USD/TRY was about 45.35 and up roughly 5.5% year-to-date, while April CPI was 32.37% and food inflation was 34.55%. At the same time, reporting described the lira’s slide as a controlled devaluation rather than a disorderly break. That combination argues for a mid-single-digit or perhaps high-single-digit move by July, but not usually an Argentina-style blowout unless pricing or policy suddenly changes. (globalinflation.org)

Brazil and Egypt are the other serious contenders. Brazil’s local Big Mac price stayed at 23.90 BRL from January 2025 through January 2026, so a stronger currency can feed through quickly into the raw measure; the BSP’s May 5 reference sheet implies about 4.96 BRL per dollar versus 5.37 in the January 2026 index, and BofA expected the real to remain supported by carry and commodities. Egypt points in the opposite direction: the January 2026 index used 47.24 EGP per dollar, but USD/EGP was about 52.72 on May 11. If burger prices in Egypt are sticky, that alone can deepen undervaluation by several points; if prices are reset upward, it offsets part of the FX move. Either way, both countries look more like mid-single-digit to low-double-digit possibilities than extreme-tail cases. (globalinflation.org)

The rest of the basket looks less likely to win. Chile’s peso was only around 890 per dollar in early May versus 883.85 in the January index, Colombia was roughly 3,727 versus 3,686.73, Mexico was roughly 17.53 versus 17.68, and India and Indonesia had only modest FX deterioration from January levels. Those countries can still move if local McDonald’s pricing changes, but on current information they look more like small to moderate movers than the likeliest maximum. (globalinflation.org)

Putting it all together, I put substantial mass on a result just above 10 pp, the heaviest mass in the low teens, and a thinner right tail driven mostly by Argentina. My rough mental buckets are: below 10 pp about 34%, 10-15 pp about 44%, 15-20 pp about 12%, 20-30 pp about 7%, and above 30 pp about 3%. That yields a forecast centered around 12-14 pp, with the biggest downside risk being that local price resets offset FX moves, and the biggest upside risk being another abrupt Argentina repricing episode. (globalinflation.org)

I started from the Big Mac Index raw-index mechanics rather than the question wording. The Economist’s public repository says the raw file contains local Big Mac prices, actual market exchange rates, dollar prices, and the raw valuation against the US dollar; the raw valuation is therefore driven by three moving parts between January and July: the local burger price, the FX rate, and the US burger price. For accessible country-by-country historical records, I used country pages that explicitly state their data source is The Economist’s GitHub dataset. On the January 2026 edition, the US baseline price was $6.12, and the ten relevant raw valuations were about Argentina -9.6%, Brazil -27.3%, Chile -11.4%, Colombia +1.5%, Egypt -56.7%, India -59.0%, Indonesia -58.8%, Mexico +0.8%, South Africa -45.1%, and Turkey -3.6%. (github.com)

The historical base rate among these same countries points to a distribution centered in the low-to-mid teens, but with an Argentina tail. Using the recent Jan-to-Jul records visible in the Economist-backed series, the largest move among the ten looks to have been roughly 9 pp in 2021, about 15 pp in 2022, about 17 pp in 2023, and then an extreme roughly 48 pp in 2024 when Argentina swung from around -33% to about +15%. Brazil, Mexico, and Turkey have also posted double-digit Jan-to-Jul swings in recent years, but nothing on the Argentina-2024 scale. That history is the main reason I keep a meaningful right tail even though my central forecast is much lower than 48 pp. (globalinflation.org)

As of early May 2026, FX has already moved enough to narrow the field. Market pages in the first week of May showed USD/BRL around 4.96 versus 5.37 in the January data, USD/MXN about 17.31 versus 17.68, USD/ARS about 1,397.98 versus 1,445.76, USD/TRY about 45.24 versus 43.19, USD/EGP about 52.92 versus 47.24, USD/INR about 94.26 versus 90.30, USD/COP about 3,739 versus 3,687, USD/CLP about 892.28 versus 883.85, the rand around 16.8 versus 16.35, and BI’s own dashboard showed JISDOR at IDR 17,362 versus 16,885 in the January Big Mac data. If local Big Mac prices were frozen and the US Big Mac also stayed at $6.12, the Jan-to-now raw-valuation move would already be about +6.1 pp for Brazil, +3.1 pp for Argentina, +2.2 pp for Mexico, and roughly -4 to -5 pp for Turkey and Egypt. That makes Brazil the strongest non-Argentina contender, while Turkey and Egypt need local price increases to overcome their weaker currencies. (tradingeconomics.com)

The main country-specific reason I still put Argentina first is that local-price inflation has not vanished even though it is far below the 2024 peak. The BCRA reported monthly inflation of 3.4% in March 2026, and its exchange-band regime continues to adjust monthly with inflation; IMF staff also described widened FX bands and framework refinements as part of the current program. Turkey is the main tail challenger because official April 2026 CPI was still 32.37% y/y and 4.18% m/m, while the IMF still expected end-2026 inflation around 23%; that is enough to produce another meaningful McDonald’s repricing round before July even if the lira keeps sliding. Egypt is volatile too: the CBE said March 2026 urban headline CPI was 15.2% y/y and 3.2% m/m, and in April it explicitly described exchange-rate depreciation as a key shock absorber. By contrast, Indonesia looks much less likely to win: BI held its policy rate at 4.75% in April, April CPI was only 2.42% y/y, and BI is openly prioritizing rupiah stability. Mexico and Brazil sit in the middle: Reuters reported Mexico’s April inflation eased to 4.45%, and Banxico’s May 7 forecast still had 2026 Q2 headline inflation around 4.1%; Brazil’s central bank still had the Selic at 14.75% after the March meeting, while official March CPI was 4.14%. (bcra.gob.ar)

Putting that together, my median forecast is 13.8 percentage points. My modal path is that Argentina ends up winning with a low-double-digit swing, most likely because another burger price step-up combines with a peso that remains stronger than it was in late January. Brazil is my second-most-plausible winner if the real stays unusually firm into the July data cut. Turkey is my most important upside-tail alternative because high monthly inflation can generate abrupt menu repricing. I therefore put most probability mass in the 10-18 pp range, some meaningful mass in the 18-30 pp range, and a small but nontrivial tail above 30 pp in case Argentina again produces a large regime-style jump. (globalinflation.org)

What will be the largest absolute change among select countries’ currencies of “% under/over valued” between the January and July 2026 editions of The Economist’s Big Mac Index?

• My most likely prediction for the largest absolute change is 21.80 percentage points (pp), with a 50% chance of falling between 15.80 and 25.80 pp.
• Argentina is the most probable country to set this maximum value due to a high-inflation environment (32-33% YoY) paired with a relatively stable or slowly depreciating official exchange rate.
• Turkey is a strong secondary candidate, as its monthly inflation (over 4% in April) is significantly outpacing its steady currency depreciation (~5.2% YTD).
• Emerging market currencies like the Mexican Peso and Colombian Peso are unlikely to see changes exceeding 10 pp due to more moderate inflation and interest rate stability.
• The absolute change depends on the interaction between local price hikes at McDonald’s and the market exchange rate versus the USD; current trends suggest these will diverge most sharply in Argentina.

Key figures

Historical context

Historically, the Big Mac Index has seen its largest shifts in countries undergoing hyperinflation or major currency regime changes. Argentina is a frequent outlier; in late 2023 and early 2024, the Argentine peso experienced a massive discrete devaluation that moved its valuation by over 30 percentage points in a single index cycle. Similarly, Turkey has seen fluctuations of 10-15 pp as the Central Bank shifted between unorthodox and orthodox monetary policies. Egypt experienced a significant shift in the January 2026 edition following the unification of its official and parallel exchange rates in 2024, which initially left the currency over 50% undervalued. These precedents establish that in high-inflation environments, the ‘menu price’ of a Big Mac often fails to move in perfect sync with a volatile exchange rate, creating the large percentage point gaps measured by this question.

Tailwinds

• Continued Argentine peso appreciation or a rigid crawling peg alongside 3% monthly inflation would aggressively push the currency toward overvaluation, maximizing the absolute change.
• Recent technical analysis suggests the South African rand could drop to 15.65 (a significant appreciation), which could surprise as a driver for a large valuation shift if paired with local price hikes.
• Supply chain disruptions in the Middle East could cause discrete, large-scale price jumps for beef and paper in markets like Egypt, independent of broad inflation trends.
• A sudden ‘catch-up’ price hike by McDonald’s in Turkey to account for cumulative inflation could create a one-time jump in the local USD price of the Big Mac.

Headwinds

• A major discrete devaluation of the Argentine peso before the July 2026 data collection would offset local price inflation, keeping the absolute valuation change lower.
• McDonald’s could choose to delay price increases in high-inflation markets to maintain ‘value platforms,’ which would lead to a smaller change in the Big Mac Index valuation.
• If the US price of a Big Mac increases significantly faster than expected, it would reduce the overvaluation of emerging market currencies, potentially muting the absolute percentage point shift.
• A strengthening US Dollar across the board could make all target currencies appear more undervalued, potentially keeping the net change for any single country below the 20 pp threshold.

Detailed reasoning

The forecast for the largest absolute change in ‘percentage points’ (pp) of Big Mac Index valuation centers on the volatile economic conditions in Argentina and Turkey. The Big Mac Index calculates currency valuation based on the gap between the implied exchange rate (the ratio of local Big Mac prices) and the actual market exchange rate. My analysis indicates that a change of 21.80 pp is most likely, driven by the divergence between high local price inflation and relatively stable or managed exchange rates.

Argentina is the primary driver of this forecast. In the January 2026 edition, the Argentine peso (ARS) was approximately 10.6% undervalued, with a local Big Mac price of 8,000 pesos. Since then, macroeconomic data from March to May 2026 shows a ‘scissors effect’: local inflation has persisted at 2.9% to 3.4% monthly, while the currency has nominally appreciated by nearly 4% in some windows or remained stable relative to the January reference. By July 2026, cumulative price increases are expected to reach 15-20%, while the Central Bank of Argentina (BCRA) Market Expectations Survey (REM) projects a moderate wholesale exchange rate of 1,460 ARS/USD. If the Big Mac price rises to approximately 10,000 ARS while the exchange rate remains near 1,460, the currency’s valuation would swing from -10.6% to roughly +10-15%, creating an absolute change of 20-25 pp.

Turkey serves as the secondary candidate. While the Turkish lira (TRY) has depreciated by about 5.2% since the start of 2026, monthly inflation has been significantly higher (reaching 4.18% in April alone). Because the local price growth of the burger is outpacing the currency’s depreciation, the Lira is expected to become ‘less undervalued.’ However, because these two factors partially offset one another, Turkey’s likely absolute move is estimated in the 10-15 pp range, placing it behind Argentina unless Argentina experiences a sudden currency devaluation that resets the gap.

Other countries in the basket, such as Mexico and Colombia, showed slight overvaluation in January but have maintained much lower inflation rates (0.2% to 0.8% monthly). Consequently, their absolute shifts are likely to remain in the single digits. Egypt and South Africa possess higher volatility than Mexico but lack the extreme inflation-exchange rate mismatch currently observed in the Argentine market. Therefore, the maximum value for the entire ten-country group is almost certainly determined by the outcome in Argentina.

Key uncertainties

• The exact date The Economist collects price data for the July edition is not public; a sudden currency move in early July versus late June could change the result significantly.
• Local franchisees (like Arcos Dorados in Latin America) have autonomy over pricing and may opt for ‘value deals’ that keep the Big Mac price lower than headline CPI.
• The US price of a Big Mac is also a variable; if it rises sharply, it offsets the valuation increases of emerging market currencies.
• Political risk in South Africa (e.g., potential impeachment risks) could lead to capital flight and a sudden rand devaluation, making it a late-stage outlier.

Conclusion

• Argentina and Turkey are the primary candidates to set the ceiling for this metric, with Argentina’s high-inflation, managed-currency regime making it the most likely source of a shift exceeding 20 percentage points.
• Decision-makers should focus on the ‘Raw Index’ column in the July 2026 Economist release, specifically watching for any sudden Argentine price hikes or currency appreciation that would drive the absolute change higher.

Question: which of ten emerging-market Big Mac raw indices will show the largest absolute Jan→Jul 2026 change, and by how many percentage points? Historical reconstruction (13 Jan→Jul intervals, 2012–24) puts the mean annual maximum at ~20.9 pp and the median at ~18.4 pp, with >30 pp only once (Argentina 2024, 47.6 pp). Forecasters agree the distribution should be centered in the high‑teens/low‑20s (roughly 16–24 pp) but with a fatter right tail in 2026 because Brazil’s large YTD BRL appreciation plus food-service inflation makes a double‑digit swing likely, while Argentina and Turkey remain high‑variance candidates due to menu‑price catch‑up vs managed FX regimes. Synthesis weights used here give ~60–65% probability that the winner falls in the 15–30 pp band, ~15–20% for a 30–40 pp outcome (Argentina/Turkey tail scenarios), ~2–3% for an Argentina‑style >50 pp extreme, and a small ~8% chance the cycle is unusually calm (<10 pp). Practical tracking guidance: use The Economist’s official big-mac-raw-index.csv USD_raw field, update each country’s Jan baseline with near‑term spot FX and any local Big Mac/menu‑price or food‑away‑from‑home CPI data, since FX moves are the highest‑frequency signal while menu‑price reports dominate realized changes.

Forecast and Reasoning

Forecast: Probability distribution:

• 5.00% chance of value below 8.0
• 10.00% chance of value below 12.0
• 20.00% chance of value below 15.0
• 30.00% chance of value below 17.0
• 40.00% chance of value below 19.0
• 50.00% chance of value below 21.5
• 60.00% chance of value below 24.0
• 70.00% chance of value below 27.0
• 80.00% chance of value below 32.0
• 90.00% chance of value below 40.0
• 95.00% chance of value below 52.5

Forecast Reasoning

We are forecasting the maximum, across 10 mostly emerging-market currencies, of the absolute Jan→Jul 2026 change in The Economist Big Mac Index “raw % under/over valued” (USD base). The max-of-10 structure materially lifts the expected outcome versus a typical single-country change.

Across the team, Forecasters 2/4 center the median in the low 20s pp, while Forecaster 3 provides the most decision-relevant calibration: using a secondary aggregator (globalinflation.org) they identify that Argentina has recently exhibited very large half-year swings (example cited near ~48 pp in 2024), implying a fat right tail even if most countries usually move 5–20 pp over six months. At the same time, Forecaster 4 argues (plausibly) that some of the extreme-tail risk from “one-off regime breaks” may be lower in 2026 than during prior discrete devaluation episodes.

Synthesis: the most likely outcome is that the maximum change is set by Argentina or Turkey and lands around ~18–28 pp, with a non-trivial chance of a quieter half-year where even the maximum is only ~10–15 pp, and a smaller (but real) chance of an Argentina-style discontinuity pushing the max above 50 pp. I therefore keep the median near ~21–22 pp, put modest probability mass below the 10 pp lower bound, and express a small open-upper tail beyond 50 pp (via p95 > 50).

An amateur forecast is likely to (a) anchor too tightly to the creator’s 10–50 pp range without modeling the max-of-10 effect, and/or (b) ignore the specific “fat-tail” contribution from Argentina evidenced by recent half-year swings. My forecast explicitly combines (1) selection effects (maximum across 10), (2) a central tendency consistent with the majority of analysts, and (3) asymmetric tail risk (small but nonzero chance the max exceeds 50 pp), while also avoiding overconfidence by keeping a fairly wide p10–p90 span. Confidence in improvement: moderate—main residual uncertainty is whether July 2026 includes any discrete FX/price regime shift in Argentina or Turkey.

Forecast rationale (numeric):

— Iteration 1 — Across the forecasts, the main logic is that the largest January-to-July change in Big Mac misvaluation should usually be modest for a six-month window, but the maximum across a volatile country set can still be sizable.

Core reasoning pattern

• The change in “% under/over valued” is driven by the interaction of:
  • exchange-rate moves
  • local price inflation / menu repricing
  • US price changes
• Because the horizon is only six months, most countries should move only by the teens, but the largest absolute change among the selected countries is more likely to land higher than a typical single-country move.

Main factors shaping the forecast

• High-volatility/high-inflation countries such as Argentina, Turkey, and Egypt are expected to dominate the maximum change if any large move occurs.
• Recent early-2026 data point to only modest FX changes and a softer dollar, which reduces the likelihood of an immediate crisis-sized swing.
• At the same time, persistent inflation and occasional menu repricing mean that even without a dramatic currency collapse, Big Mac valuation gaps can still shift noticeably.

Consensus view

• The forecasts broadly cluster around a mid-teens to mid-20s percentage-point maximum change, with a central tendency around ~19–30 pp.
• This reflects the belief that large but not extreme changes are the most plausible outcome.

Disagreement / uncertainty

• The main difference is in the right tail:
  • one view is somewhat more conservative, centering near the low 20s and allowing a meaningful chance of a larger jump;
  • another is more cautious, emphasizing a heavier tail for discrete devaluations, regime shifts, or sudden repricing events that could push the change above 50 pp.
• There is also recognition of a lower tail: if FX and local prices remain unusually stable, the maximum change could stay under 10 pp.

Bottom line

The shared forecasting approach is that the largest absolute change will most likely be driven by one volatile emerging-market currency and end up in the teens to mid-20s pp, while rare shock scenarios keep substantial probability mass on much larger moves.

— Iteration 2 — The forecasts converge on the idea that the largest Jan→Jul 2026 change in “% under/over valued” will most likely come from one of the more volatile emerging-market currencies, rather than from the more stable countries in the set.

Main reasoning patterns

• Volatility concentration matters: The biggest swing is expected to be driven by Argentina, Turkey, or Egypt, where Big Mac misvaluation can shift sharply over a six-month window.
• Most countries should move modestly: For relatively stable emerging markets, the expected change is usually in the low-to-mid single digits or low teens percentage points, so they are less likely to produce the maximum.
• Macro context can nudge some currencies: A softer USD and stronger Brazilian real point to moderate changes in Brazil, while oil price movements may affect Mexico and Colombia, but these are usually not enough to create the largest swing.
• Discrete events dominate the tail: A devaluation, revaluation, policy shift, or pricing methodology change is seen as the main path to an outsized jump, especially in historically fragile currencies.

Areas of consensus

• The maximum absolute change is likely in the mid-20s percentage points, with one estimate slightly lower and another slightly higher.
• There is broad agreement that extreme outcomes above 50 pp are possible but unlikely, reserved for a major FX event.
• The overall uncertainty is moderate to high, because the statistic is a maximum across multiple countries, which increases the chance of a larger move.

Main difference in emphasis

• One rationale leans a bit more toward a higher central estimate in the high-20s due to the “max across 10 countries” effect.
• The other is slightly more conservative, centering in the mid-20s while still allowing a meaningful tail.

Bottom line

The shared view is that the largest change will probably be a moderate-to-large swing driven by a volatile EM currency, with a central expectation around the mid-to-high 20s percentage points and a nontrivial chance of a much larger move if a disruptive FX or policy event occurs.

— Iteration 3 — Across the forecasts, the main expectation is that the largest absolute Jan→Jul 2026 change in “% under/over valued” will likely be in the mid-20s percentage points, with a central estimate around 23–24 pp.

Key reasoning patterns and factors

• Largest moves likely come from the most volatile EM currencies in the set, especially Turkey, Egypt, or Argentina, where inflation, policy uncertainty, and FX instability can drive sizable half-year shifts.
• The Big Mac Index change is driven by both exchange-rate moves and local price changes. Forecasts assume:
  • some FX adjustment/stabilization in certain currencies,
  • continued inflation pass-through in high-inflation economies,
  • and only a modest change in U.S. benchmark prices.
• Because the question asks for the maximum across several countries, the expected outcome is somewhat larger than for any single country’s change.
• Typical half-year emerging-market dynamics are judged to produce meaningful but not usually extreme changes, often in the 5–20 pp range, with the maximum across countries landing somewhat above that.

Areas of consensus

• Strong agreement that the answer is not near zero and not usually above 50 pp.
• Strong agreement that the most likely result is around the low-to-mid 20s pp.
• Broad agreement that regime shifts, policy shocks, or data revisions are the main sources of unusually large outcomes.

Uncertainty and tails

• Forecasts allow for quiet-market scenarios where all countries move modestly, implying a lower tail below 10 pp.
• They also keep a small but nontrivial chance of very large jumps (around 50 pp or more) if there is a sharp devaluation, policy intervention, or major pricing change in one of the more unstable currencies.

Overall, the collective reasoning is that the maximum absolute change will likely be driven by one volatile EM currency and end up in the low-to-mid 20s percentage points, with meaningful uncertainty but a clear bias toward a moderate-to-large shift rather than an extreme outlier.

SUMMARY

Question: What will be the largest absolute change among select countries’ currencies of “% under/over valued” between the January and July 2026 editions of The Economist’s Big Mac Index? Final Prediction: Probability distribution:

• 10.00% chance of value below 11.666667
• 20.00% chance of value below 14.0
• 40.00% chance of value below 18.0
• 60.00% chance of value below 22.666667
• 80.00% chance of value below 30.0
• 90.00% chance of value below 37.666667

Total Cost: extra_metadata_in_explanation is disabled Time Spent: extra_metadata_in_explanation is disabled LLMs: extra_metadata_in_explanation is disabled Bot Name: extra_metadata_in_explanation is disabled

Report 1 Summary

Forecasts

Forecaster 1: Probability distribution:

• 10.00% chance of value below 12.0
• 20.00% chance of value below 14.5
• 40.00% chance of value below 18.5
• 60.00% chance of value below 23.0
• 80.00% chance of value below 30.0
• 90.00% chance of value below 37.0

Forecaster 2: Probability distribution:

• 10.00% chance of value below 12.0
• 20.00% chance of value below 14.5
• 40.00% chance of value below 18.5
• 60.00% chance of value below 23.0
• 80.00% chance of value below 30.0
• 90.00% chance of value below 38.0

Forecaster 3: Probability distribution:

• 10.00% chance of value below 11.0
• 20.00% chance of value below 13.0
• 40.00% chance of value below 17.0
• 60.00% chance of value below 22.0
• 80.00% chance of value below 30.0
• 90.00% chance of value below 38.0

Research Summary

The research analyzes potential changes in the valuation of select currencies as indicated by The Economist’s Big Mac Index between January and July 2026. It highlights the current values from January 2026, where Argentina is notably overvalued at +20.1%, while Turkey, Egypt, India, and several other countries are significantly undervalued, with Turkey at -58.9% and Egypt at -56.8%. The study emphasizes Argentina’s unique position, as it has experienced further appreciation of its currency amidst high domestic inflation, suggesting a potential increase in its overvaluation to between +30% and +40% by July 2026. Conversely, Turkey and Egypt are expected to show more stable or moderate changes unless significant devaluation events occur.

The research also discusses historical trends, indicating that highly volatile currencies like those of Argentina and Turkey can see substantial shifts (15–40+ percentage points) in their Big Mac Index values over a six-month period. It identifies key risk factors that could influence these changes, including Argentina’s exchange rate policy, geopolitical tensions, and local price adjustments. Overall, Argentina is positioned as the most likely candidate for the largest absolute change in currency valuation, with a plausible range of 10–35 percentage points, while other countries may experience more moderate fluctuations.

Sources used in the research include:

• The Economist’s Big Mac Index
• Quantum Finanzas
• Facimex Valores
• Historical data on currency volatility and economic indicators.

(Note: Specific links were not provided in the original text.)

RESEARCH

Report 1 Research

Research Rundown: Largest Absolute Change in Big Mac Index (January → July 2026)

Current January 2026 Big Mac Index Values (Raw Index, Select Countries)

Based on available data from the January 2026 edition [2][5]:

The US baseline Big Mac price is approximately $5.79 [1][2].

Key Currency Dynamics (January–May 2026)

Argentina (Prime Candidate for Largest Swing):

• Argentina was already the second-most overvalued currency (after Switzerland) in the January 2025 edition [12], and remained significantly overvalued in January 2026 at +20.1% [2].
• Since January 2026, the Argentine peso has appreciated further. The official dollar dropped from ~$1,415 in January to ~$1,340–1,370 by April–May 2026 (a ~5.4% nominal appreciation) [13][17].
• Simultaneously, domestic inflation has been running at ~3–3.5% monthly [8][12], pushing local Big Mac prices higher in peso terms.
• Analysts estimate the peso became roughly 10% more overvalued in just two months (February–April) due to the combination of peso appreciation and continued domestic inflation [12].
• Quantum Finanzas noted the peso appreciated 5.1% nominally and 12.2% in real terms in early 2026 [14].
• Facimex Valores warns of potential pressures between June and August due to the World Cup and carry trade closures, projecting ~8% real depreciation by year-end — but the currency would still remain historically appreciated [14].
• If current trends continue or even partially persist through July, Argentina’s overvaluation could increase from +20% to potentially +30–40%+, representing a 10–20+ pp absolute change.
• However, if the projected mid-year correction materializes (World Cup capital outflows, carry trade unwinding), Argentina could also see a reversal, meaning the change might be smaller or could go in either direction.

Turkey:

• Turkey was deeply undervalued at approximately -58.9% in January 2026 [5]. The Turkish lira has been under ongoing depreciation pressure, but gradual controlled depreciation typically produces smaller inter-edition swings unless there’s a sudden devaluation event.

Egypt:

• The Egyptian pound was at -56.8% undervalued in January 2026 [5]. As of May 2026, the pound is trading around 52.52 EGP/USD [16], suggesting relative stability. Egypt underwent a major devaluation in March 2024, and the currency has been more stable since.

Other Countries:

• Brazil, Chile, Colombia, Mexico, India, Indonesia, and South Africa tend to show more moderate changes (typically 5–15 pp between editions), though commodity price swings or idiosyncratic shocks can push changes higher [4].

Historical Base Rates & Reference Classes

Typical inter-edition swings (January → July):

• For stable emerging markets (India, Indonesia, Mexico), changes are typically 3–10 pp between editions.
• For moderately volatile currencies (Brazil, Chile, Colombia, South Africa), changes are typically 5–15 pp.
• For highly volatile currencies (Argentina, Turkey, Egypt), changes can reach 15–40+ pp in a single half-year period [4][6].

Notable historical examples:

• Argentina has shown the most extreme volatility in the Big Mac Index historically, moving from deep undervaluation to top-of-the-index overvaluation. After the December 2023 devaluation, Argentina’s index value swung by ~50+ pp. The ongoing appreciation trend in 2026 makes it the leading candidate for the largest swing again [4][5].
• Egypt saw a massive swing after its March 2024 devaluation (moving from ~-10% to deeply undervalued).
• Turkey has shown persistent drift toward deeper undervaluation, but typically in increments of 5–15 pp per half-year unless a crisis event occurs.

Maximum among 10 countries: Even in relatively calm periods, the maximum absolute change among 10 emerging market currencies is typically 10–20 pp. In volatile periods (which 2026 qualifies as given geopolitical tensions, Iran conflict, commodity price shifts, and Argentina’s unique dynamics), the maximum can reach 20–40+ pp [4].

Prediction Markets

I found no active prediction markets specifically targeting the Big Mac Index changes. This is a niche economic indicator question unlikely to attract dedicated market liquidity. The absence of prediction market data means there’s no market-derived probability distribution to reference.

Key Risk Factors to Monitor (May → July 2026)

1. Argentina’s exchange rate policy: The peso’s stability around $1,370–1,420 is being maintained by seasonal agricultural dollar inflows. Between June and August, these inflows weaken, potentially triggering depreciation [14][15]. A sharp correction could either amplify or reverse the overvaluation trend.
2. Iran conflict / energy prices: The war in Iran has driven up fuel prices (26–28% increase in Argentina in March) and creates global uncertainty [15].
3. FIFA World Cup (June–July 2026): Analysts specifically flag this as a risk event for Argentina’s exchange rate due to capital outflows [14].
4. US dollar trajectory: The dollar has been weakening in 2025–2026 after a 15-year strength period [4], which tends to reduce undervaluation readings for most emerging markets.
5. Local Big Mac price adjustments: McDonald’s can adjust local prices, and large inter-edition changes sometimes reflect price hikes rather than pure exchange rate moves.

Summary Assessment

Most likely candidate for largest absolute change: Argentina, given:

• Already extreme overvaluation (+20%) in January 2026
• Continued peso appreciation and domestic inflation through May 2026
• Potential for a mid-year correction creating additional volatility
• Historical pattern of Argentina producing the most extreme Big Mac Index swings

Plausible range for the largest absolute change: 10–35 pp, with the central expectation around 15–25 pp, driven primarily by Argentina. If Argentina experiences a disorderly mid-year correction, the swing could be even larger. If Argentina remains relatively stable, Turkey or another country experiencing a currency shock could produce the largest change, though likely in the 10–20 pp range.

FORECASTS

R1: Forecaster 1 Reasoning

Looking at this Big Mac Index forecasting question, I need to carefully analyze the potential for currency valuation swings among the 10 specified emerging market countries.

Pre-Analysis Framework

(a) Time left until outcome is known: Approximately 3 months. Today is May 11, 2026; the July 2026 edition should publish in July, with resolution based on data as of August 12, 2026.

(b) Outside view - reference class and base rates:

• Stable EM currencies (India, Indonesia, Mexico): typically 3-10 pp change between editions
• Moderately volatile currencies (Brazil, Chile, Colombia, South Africa): typically 5-15 pp
• Highly volatile currencies (Argentina, Turkey, Egypt): can reach 15-40+ pp in a single half-year
• Maximum among 10 EM currencies: 10-20 pp in calm periods, 20-40+ pp in volatile periods
• Historical extreme: Argentina swung 50+ pp after December 2023 devaluation

(c) Inside view - key specific evidence:

• Argentina is at +20.1% overvalued in January 2026 (unusual position)
• Analysts estimate Argentina’s peso became ~10% MORE overvalued in just Feb-April 2026
• Peso appreciated ~5.4% nominally since January while domestic inflation runs 3-3.5% monthly
• Quantum Finanzas noted 12.2% real appreciation in early 2026
• Mid-year risks: World Cup capital outflows, carry trade unwinding could cause correction
• Turkey (-58.9%) and Egypt (-56.8%) are deeply undervalued but relatively stable

(d) Outcome if nothing changed: If rates and prices froze today, Argentina’s change from January is likely already 10-12 pp based on appreciation and inflation accumulated through May.

(e) Outcome if current trend continued: Argentina’s overvaluation could increase from +20% to +30-40%+, representing 10-20+ pp change. With remaining 2 months of trend continuation, 15-25 pp seems plausible.

(f) Expectations of experts and markets: No prediction markets found. Question creator bounds suggest 10-50 pp range. Analysts project potential mid-year pressures on Argentina but expect it to remain historically appreciated.

(g) Low outcome scenario: Argentina’s peso corrects back toward January levels, domestic inflation moderates, other 9 countries remain stable. Maximum change could be only 8-12 pp.

(h) High outcome scenario: Argentina experiences a disorderly currency crisis/sharp devaluation (similar to December 2023), or another country like Turkey has a sudden major currency event. Maximum swing could exceed 45-60 pp.

Rationale

Starting from the base rate of 10-20 pp for maximum change among 10 EM currencies in typical periods, several factors push upward:

1. Argentina’s current dynamics are exceptional - already showing ~10 pp change through May, with 2 months remaining
2. Both appreciation and depreciation scenarios produce large swings - if the peso corrects sharply, the change could be even larger than continued appreciation
3. 2026 is volatile - Iran conflict, World Cup, commodity price shifts create elevated uncertainty
4. Historical precedent - Argentina routinely produces the most extreme Big Mac Index swings

The median should be around 20-21 pp, reflecting Argentina’s likely dominance. The distribution should have meaningful probability above 30 pp (crisis scenarios) while keeping the lower tail recognizing that 10 countries provide multiple opportunities for at least moderate swings.

“ Percentile 0.1: 5 Percentile 1: 7 Percentile 5: 10 Percentile 10: 12 Percentile 20: 14.5 Percentile 30: 16.5 Percentile 40: 18.5 Percentile 50: 20.5 Percentile 60: 23 Percentile 70: 26 Percentile 80: 30 Percentile 90: 37 Percentile 95: 45 Percentile 99: 58 Percentile 99.9: 75 “

R1: Forecaster 2 Reasoning

Looking at this question, I need to forecast the largest absolute change in the Big Mac Index’s “% under/over valued” among 10 emerging market currencies between January and July 2026.

Analysis Framework

(a) Time until outcome known: Approximately 3 months from today (2026-05-11) until July 2026 edition publication, with final resolution at 2026-08-12.

(b) Outside view - reference class and base rates:

• Stable emerging markets (India, Indonesia, Mexico): typically 3-10 pp between editions
• Moderately volatile currencies (Brazil, Chile, Colombia, South Africa): typically 5-15 pp
• Highly volatile currencies (Argentina, Turkey, Egypt): 15-40+ pp possible
• Maximum among 10 EM currencies: 10-20 pp in calm periods; 20-40+ pp in volatile periods
• Historical extremes: Argentina swung 50+ pp after the December 2023 devaluation

(c) Inside view - key specific evidence:

• Argentina at +20.1% overvalued in January 2026 (second-most overvalued globally)
• Argentine peso appreciated ~5.4% nominally since January with 3-3.5% monthly inflation
• Analysts estimate Argentina became ~10% more overvalued in Feb-Apr alone
• Projected mid-year pressure (June-August) from World Cup capital outflows
• Turkey and Egypt showing relative stability at deeply undervalued levels

(d) Outcome if nothing changed: Hypothetically 0 pp, but exchange rates and local prices always move - minimum plausible change is ~5-8 pp.

(e) Outcome if current trend continued: Argentina’s overvaluation could increase from +20% to +30-40%, yielding 10-20+ pp change. This would likely be the maximum among all 10 countries.

(f) Expectations of experts/markets: No prediction markets found. Analysts project Argentina remains the key driver with “8% real depreciation by year-end” possible but still at historically appreciated levels.

(g) Low outcome scenario: Argentina experiences a controlled, gradual mid-year correction that largely offsets earlier appreciation. Other currencies remain stable. Maximum change among all 10 countries is only 8-12 pp.

(h) High outcome scenario: Argentina experiences either: (1) continued aggressive appreciation + inflation pushing overvaluation to +40-50%, or (2) a disorderly devaluation triggered by World Cup capital outflows and carry trade unwinding. Alternatively, Turkey or Egypt experiences a sudden currency crisis. Maximum change reaches 40-60+ pp.

Rationale

Starting from the base rate of 15-20 pp for the maximum change among 10 EM currencies in normal conditions, I adjust upward because:

1. Argentina is already at an extreme +20% overvaluation and showing continued appreciation
2. Current geopolitical instability (Iran conflict, commodity price volatility) elevates risk
3. Specific mid-year risk events (World Cup, seasonal agricultural dollar inflows weakening)
4. 2026 qualifies as a “volatile period” based on research

However, I also account for potential moderation if Argentina’s expected mid-year correction materializes in a controlled fashion. The distribution has significant right-tail risk given historical Argentina volatility.

Central estimate: ~20 pp, driven by Argentina Plausible range: 12-35 pp covers most likely outcomes Tail scenarios: 8-10 pp (stability) to 50+ pp (crisis)

“ Percentile 0.1: 6 Percentile 1: 8 Percentile 5: 10.5 Percentile 10: 12 Percentile 20: 14.5 Percentile 30: 16.5 Percentile 40: 18.5 Percentile 50: 20.5 Percentile 60: 23 Percentile 70: 26 Percentile 80: 30 Percentile 90: 38 Percentile 95: 48 Percentile 99: 65 Percentile 99.9: 85 “

R1: Forecaster 3 Reasoning

Looking at this forecasting question, I need to analyze the likely largest absolute change in Big Mac Index “% under/over valued” values among the 10 listed countries between January and July 2026.

(a) Time remaining: About 2 months until the July 2026 edition, with final resolution by August 12, 2026.

(b) Outside view / Base rates:

• Stable emerging markets (India, Indonesia, Mexico): typically 3-10 pp changes between editions
• Moderately volatile currencies (Brazil, Chile, Colombia, South Africa): typically 5-15 pp
• Highly volatile currencies (Argentina, Turkey, Egypt): can reach 15-40+ pp per half-year
• Maximum among 10 EM currencies: typically 10-20 pp in calm periods, 20-40+ pp in volatile periods
• Historical precedent: Argentina’s December 2023 devaluation caused a 50+ pp swing

(c) Inside view / Key specific evidence:

• Argentina is already at +20.1% overvalued (unusual position) in January 2026
• The peso has appreciated further since January (~5% nominal, ~12% real appreciation)
• Continued domestic inflation (3-3.5% monthly) is pushing local Big Mac prices higher
• Analysts estimate the peso became ~10% more overvalued just February-April
• However, June-August risk factors (World Cup capital outflows, carry trade unwinding) could trigger correction
• Turkey and Egypt remain deeply undervalued but relatively stable

(d) Outcome if nothing changed: With current January 2026 values locked in and only price adjustments, likely 5-10 pp maximum change.

(e) Outcome if current trend continued: Argentina’s overvaluation could increase from +20% to +30-40%+, suggesting 10-20+ pp change. This is the central expectation.

(f) Expert/market expectations: No active prediction markets found. Research suggests central expectation of 15-25 pp, with Argentina as the primary driver.

(g) Low outcome scenario: All currencies remain remarkably stable through July; Argentina’s peso stabilizes at current levels with minimal price changes; no currency crises occur anywhere. Maximum change around 8-12 pp.

(h) High outcome scenario: Argentina experiences a disorderly mid-year currency crisis (triggered by World Cup capital flight or loss of confidence), causing a swing from +20% overvalued to significantly undervalued—or continued appreciation pushes overvaluation to extreme levels before a sharp correction. A Turkish lira or Egyptian pound crisis could also produce a 40-60+ pp swing.

Rationale: Starting from the base rate that the maximum change among 10 volatile emerging market currencies is typically 10-20 pp in normal times and 20-40+ pp in volatile times, I adjust upward given:

1. Argentina’s unusual starting position (+20% overvalued) and ongoing appreciation trend
2. The 2026 environment being classified as volatile (Iran conflict, commodity price swings)
3. Specific analyst projections showing 10%+ additional overvaluation accumulation since January
4. The June-August risk period creates potential for both continued appreciation OR sharp correction

The central case is Argentina driving a 15-25 pp change. The tail risks are substantial given Argentina’s history and identified mid-year risk factors.

“ Percentile 0.1: 5 Percentile 1: 7 Percentile 5: 9 Percentile 10: 11 Percentile 20: 13 Percentile 30: 15 Percentile 40: 17 Percentile 50: 19 Percentile 60: 22 Percentile 70: 25 Percentile 80: 30 Percentile 90: 38 Percentile 95: 48 Percentile 99: 65 Percentile 99.9: 85 “

Agent Forecast (numeric, confidence: low)

• 15-20: 29.0%
• 10-15: 25.0%
• 20-25: 18.0%
• 25-30: 10.0%
• 30-40: 7.0%

Base Rate: In the July 2025 to January 2026 half-year, the largest changes among these 10 countries were Argentina at ~30 pp (extraordinary) and Colombia at ~12 pp. In typical 6-month periods for this volatile emerging-market group, the maximum country change is historically 10-25 pp, with right-skewed tails when crisis or sharp policy shifts occur.

Initial Reasoning:

• The largest absolute change among the 10 countries between January 2026 and July 2026 will most likely be driven by Argentina.
• Argentina’s January 2026 Big Mac Index was -9.6% (undervalued), with a local price of 8,000 pesos at 1,449 ARS/USD.
• The peso has since appreciated ~3.3% to 1,401 by May 2026, and Argentina’s 2026 annual inflation is forecast at 30.5% (~14-15% cumulative over 6 months).
• Combined, this pushes Argentina’s dollar Big Mac price significantly higher toward $6.50-6.80, shifting Argentina from -10% (undervalued) to approximately +3-7% (overvalued), yielding an absolute change of ~13-17 pp.
• Mexico (currently +1% with barely any MXN movement), South Africa (-45%, ZAR stable), Turkey (-4%, gradual depreciation offset by local inflation), and Brazil (-27%, real has appreciated but change is ~6-9 pp) are smaller candidates.
• The 10-15 pp bin is the modal outcome, with meaningful probability mass in 15-20 pp if Argentina’s dynamics are more extreme.

Key Uncertainties:

• Argentina’s exchange rate trajectory — peso could appreciate further OR depreciate sharply if policy shifts; either tail produces different absolute changes
• Turkey’s TRY/USD path and whether monetary policy normalization produces a 15-25 pp swing from its near-equilibrium starting point
• Egypt’s currency regime — potential for another step devaluation that creates a large swing
• Firm-level Big Mac price-setting in high-inflation economies often lags or leads CPI, adding two-sided uncertainty
• US Big Mac price in July 2026 (estimated $6.30-6.45, affected by USD depreciation outlook)
• Whether the question resolves on the listed 10 countries only — small chance one drops from coverage

Evidence Sources (11):

• BigMacIndex.app - January 2026 Economist Data
• Statbase - Big Mac Index Data Countries 2000-2026
• Infobae - Índice Big Mac Argentina enero 2026
• El Tiempo - Colombia Big Mac Index January 2026
• Trading Economics - Argentina Peso Exchange Rate
• Reuters via Yahoo Finance - Argentina 2026 inflation forecast
• Exchange-rates.org - USD/MXN 2026 history
• Wise - USD to TRY exchange rate history 2026
• Wise - USD to BRL exchange rate history
• MUFG Research - 2026 Annual Foreign Exchange Outlook
• World Population Review - Big Mac Index 2025 (July 2025 data)

Grounding Facts (passed to reviewers):

1. Today’s date is May 11, 2026.
2. The question requires comparing the January and July 2026 editions of The Economist’s Big Mac Index.
3. The January 2026 Big Mac Index values are: Argentina -9.6% undervalued, Brazil -27% undervalued, Colombia +1.5% overvalued, Egypt -56.8% undervalued, India -58.9% undervalued, Indonesia -58.9% undervalued, Mexico +1% overvalued, South Africa -45.1% undervalued, and Turkey -4% undervalued.
4. The Argentine peso has appreciated approximately 3.3% from January to May 11, 2026, with the ARS/USD exchange rate moving from an average of 1,448 to 1,401.
5. Analysts expect Argentina’s 2026 annual inflation to be 30.5%, implying 14-15% cumulative inflation over January-July 2026.
6. The Turkish lira has depreciated 5.5% year-to-date in 2026, moving from 42.9948 TRY/USD on January 1, 2026, to 45.38 TRY/USD on May 11, 2026.
7. The Brazilian real has appreciated significantly from late 2025 peaks, with the BRL/USD exchange rate at 4.898 on May 11, 2026.
8. The Mexican peso’s MXN/USD exchange rate moved from 17.47 on January 31, 2026, to 17.17 in May 2026.
9. MUFG Research forecasts the US dollar to depreciate approximately 5% in 2026.

Draft: 10-15: 34.0%, 15-20: 28.0%, 20-25: 15.0%, 25-30: 8.0%, Below 10: 8.0%

Reviewer Panel:

Reviewer (reasoning)

The draft’s Argentina‐centric projection rests on broad CPI and partial exchange‐rate moves rather than observed Big Mac price adjustments, and it neglects other high‐inflation/high‐volatility cases like Turkey or Egypt. It also omits any corporate pricing pass‐through assumptions and historical base‐rate volatility of Big Mac index swings, making its concentration in the 10–15 pp bin too narrow.

Objections:

• Relies on aggregate CPI forecasts instead of actual Big Mac price changes, ignoring firm‐level pricing behavior.
• Underestimates Turkey (high inflation plus currency depreciation) and Egypt as candidates for >15 pp shifts.
• Fails to reference historical quarterly Big Mac index volatility or pass‐through rates, skewing calibration toward a tight Argentina outcome.

Reviewer (calibration)

The forecast relies heavily on a specific scenario for Argentina involving a significant nominal peso appreciation (or stability) despite substantial domestic inflation, leading to a large real appreciation. While possible under current policies, this specific exchange rate behavior for a high-inflation economy is a strong assumption. The forecast also undervalues the potential for other volatile economies like Turkey, which, starting closer to equilibrium, could experience substantial shifts from similar real exchange rate movements.

Objections:

• The forecast assumes the Argentine peso will remain relatively stable or appreciate nominally (1449 to 1401 ARS/USD) between January and July 2026, while domestic inflation is 14-15%. This implies a substantial real appreciation that may be difficult to sustain and could lead to an overestimation of Argentina’s absolute change compared to scenarios where the peso depreciates more in line with inflation.
• The forecast dismisses Turkey’s potential for a large change too quickly. Given its history of high inflation and currency volatility, and its starting point of -4% (close to equilibrium), Turkey could easily see a 15-25 percentage point shift in either direction due to aggressive monetary policy, capital flows, or renewed economic instability, making it a strong contender for the largest change.
• The calculation of the absolute change for Argentina implicitly assumes the US Big Mac price remains constant, despite a verified fact indicating a 5% projected US dollar depreciation in 2026. An increase in the US Big Mac price would slightly dampen the ‘overvalued’ percentage for Argentina.

Reviewer (fact-checker)

1 factual error(s). 5 unsupported claim(s). Verdict: minor_issues

Unsupported claims:

• pushes Argentina’s dollar Big Mac price significantly higher toward $6.50-6.80
• shifting Argentina from -10% (undervalued) to approximately +3-7% (overvalued)
• yielding an absolute change of ~13-17 pp
• Brazil … change is ~6-9 pp
• The 10-15 pp bin is the modal outcome, with meaningful probability mass in 15-20 pp if Argentina’s dynamics are more extreme

Objections:

• [minor] local price of 8,000 pesos at 1,449 ARS/USD — Corpus says: Infobae: exchange rate used 1,445.76 ARS/USD; Trading Economics: Jan 2026 avg 1,448

Adjustment Rationale:

Adjusted distribution in response to two substantive reviewer critiques. Reduced 10-15 pp bin from 0.34 to 0.25 because: (a) my Argentina forecast assumed substantial real peso appreciation (~17-18% real terms over 6 months) that is a strong policy-dependent assumption — if the peso depreciates closer to inflation, Argentina’s change shrinks; if it appreciates more, the change grows past 15 pp; (b) Turkey was dismissed too quickly given it starts at -4% (near equilibrium) and has high inflation/currency volatility — a 15-25 pp swing is plausible; (c) firm-level Big Mac pricing in high-inflation economies (Argentina, Turkey, Egypt) often deviates from CPI, adding two-sided uncertainty I had not adequately captured. Shifted mass into 15-20 (now 0.29), 20-25 (now 0.18), and lifted tail bins (25-30: 0.10, 30-40: 0.07) to reflect meaningful probability that Turkey, Egypt, or a more dramatic Argentina swing produces the maximum. Lowered confidence from medium to low given the reviewers correctly noted multiple unquantified uncertainties: actual Big Mac price pass-through rates, exchange rate trajectories for high-volatility currencies, and US Big Mac price changes (potentially affected by ~5% USD depreciation in 2026).

forecast_sdk | 810.4s | research $1.4714 + reviewers $0.0130 + reconcile $0.1511 = $1.6355

Extracted Percentile Values: {0.1: 6.0, 1.0: 7.4, 5.0: 8.9, 10.0: 9.8, 15.0: 10.6, 20.0: 11.3, 25.0: 12.0, 30.0: 12.8, 35.0: 13.5, 40.0: 14.2, 45.0: 14.8, 46.0: 15.0, 47.0: 15.1, 48.0: 15.3, 49.0: 15.5, 50.0: 15.7, 51.0: 15.9, 52.0: 16.1, 53.0: 16.3, 54.0: 16.5, 55.0: 16.8, 60.0: 17.7, 65.0: 18.8, 70.0: 20.1, 75.0: 21.8, 80.0: 24.0, 85.0: 27.2, 90.0: 31.5, 95.0: 37.5, 99.0: 48.5, 99.9: 62.0}

Model’s Answer: Step one is to anchor on the exact metric. The raw Big Mac misvaluation is just the local Big Mac price converted into U.S. terms, divided by the U.S. Big Mac price, minus one. So the change from January to July is driven by three things: local Big Mac price inflation, the currency move versus the U.S. dollar, and the U.S. Big Mac price change. The question asks for the maximum absolute change across ten countries, not the average.

Step two is to weigh the best evidence. The highest-value sources here are the Economist January 2026 raw index itself and current FX data through May 2026. Those show Colombia at +1.5, Mexico at +0.8, and Turkey at -3.5 in January, while secondary summaries imply India, Indonesia, Egypt, and South Africa were deeply undervalued. On the FX side since January, Egypt has weakened the most, Turkey has weakened moderately, and Argentina has actually strengthened somewhat. Inflation is still high in Argentina, Turkey, and likely Egypt.

Step three is to translate that into likely July moves. A key subtlety is that a deeply undervalued country can have a big percentage FX move but still only a modest percentage-point move in the Big Mac misvaluation, because its starting burger-in-USD ratio is low. That makes Argentina and Turkey more dangerous candidates for the maximum than Egypt, despite Egypt’s bigger FX move so far. Argentina looks like the modal winner: if it started near fair value and gets several more months of high local price inflation with a flat-to-strong peso, it can produce a low-teens to high-teens percentage-point change by July. Turkey is the next most plausible contender. Mexico, Colombia, Brazil, Chile, India, Indonesia, and South Africa look less likely to produce the max unless they get a sharp June-July FX move.

Step four is to account for time remaining and uncertainty. There are only about two months from today to the expected July edition, so truly extreme outcomes need a discrete shock: a fresh devaluation, a burst of local menu repricing, or a correction in the Economist data. That keeps most mass in the 10 to 25 range, but with a meaningful right tail.

The assumptions most likely to matter are these. First, I am assuming Argentina’s January raw reading was near enough to parity that its inflation-plus-FX path can generate the largest move; I put about a 35% chance that this is materially wrong, which is the main reason for extra lower-tail uncertainty. Second, I am assuming no sudden one-off currency break in Egypt or Turkey before the July snapshot; I put about a 15% chance of that failing, which drives much of the upper tail. Third, I am assuming the July edition appears on time with broadly consistent country coverage and methodology; I put about a 5% chance of something odd here, which modestly fattens both tails.

A low outcome would happen if Argentina’s burger price increases are small or largely offset by FX moves, and no other listed country has a June-July shock. I think sub-10 is unlikely but very live, around low-teens probability. A high outcome would happen if one of Argentina, Turkey, or Egypt gets a discrete currency or pricing jump before the July snapshot; I think above 30 is possible but still clearly minority, around 10% or a bit less. Above 50 needs an outright shock and is very unlikely, but not impossible on this horizon.

Percentile .1: 6.0 Percentile 1: 7.4 Percentile 5: 8.9 Percentile 10: 9.8 Percentile 15: 10.6 Percentile 20: 11.3 Percentile 25: 12.0 Percentile 30: 12.8 Percentile 35: 13.5 Percentile 40: 14.2 Percentile 45: 14.8 Percentile 46: 15.0 Percentile 47: 15.1 Percentile 48: 15.3 Percentile 49: 15.5 Percentile 50: 15.7 Percentile 51: 15.9 Percentile 52: 16.1 Percentile 53: 16.3 Percentile 54: 16.5 Percentile 55: 16.8 Percentile 60: 17.7 Percentile 65: 18.8 Percentile 70: 20.1 Percentile 75: 21.8 Percentile 80: 24.0 Percentile 85: 27.2 Percentile 90: 31.5 Percentile 95: 37.5 Percentile 99: 48.5 Percentile 99.9: 62.0

Forecast: median = 15.9544

• The inflation-indexed exchange rate band for Argentina is expected to rise significantly, allowing for a meaningful depreciation of the peso without a formal devaluation.
• Argentina’s peso is projected to depreciate by approximately 15-18% from its January 2026 value due to the faster-than-expected adjustments in the band.
• The government’s commitment to avoiding a devaluation reduces the likelihood of a crisis scenario, but the mechanical drift within the band still suggests notable currency changes.
• Other countries’ currencies, such as Brazil’s and Turkey’s, are also expected to experience movements that will contribute to the overall changes in currency valuations.
• The resolution of data discrepancies regarding the January 2026 figures ensures that the analysis is based on accurate and authoritative sources.

Forecast (percentiles, aggregated):

• p10: 10.0
• p25: 14.0
• p50: 18.5
• p75: 26.5
• p90: 38.0

Per-model forecasts:

• 1: p10=10.5, p25=13.0, p50=17.0, p75=24.0, p90=34.0
• 2: p10=10, p25=14, p50=20, p75=29, p90=42
• 3: p10=11.5, p25=14.5, p50=19.5, p75=27.5, p90=38.5

Rationale: Summary The estimate for the largest absolute change in Big Mac Index valuations between January and July 2026 relies on an analysis of historical volatility across the ten specified emerging markets. Historically, maximum changes among these countries during a six-month window have typically clustered between 8 and 20 percentage points, driven by routine foreign exchange fluctuations or moderate policy shifts. However, the presence of chronically volatile economies—most notably Argentina, Egypt, and Turkey—creates a high baseline probability for larger adjustments. With ten candidates, the metric captures the single most extreme event across the group, naturally skewing the distribution upwards. The median estimate of 18.5 percentage points sits slightly above the historical median, reflecting ongoing macroeconomic turbulence, recent shifts to floating-band currency regimes, and elevated tariff-related volatility in emerging markets in 2026. The 90th percentile stretches to 38.0 percentage points to account for the possibility of a severe, sudden devaluation resembling Argentina’s 40-point shift in 2024.

Strongest Arguments for Higher Values

• The target basket includes several countries prone to macroeconomic instability. A sudden currency crisis, hyperinflationary spiral, or major monetary policy adjustment in Argentina, Egypt, or Turkey would guarantee a high resolution.
• Argentina recently introduced a new floating-band exchange regime in January 2026 amidst continued peso weakness and central bank reserve losses, setting the stage for potentially massive valuation swings.
• Global trade tensions and anticipated tariff-driven volatility throughout 2026 disproportionately impact emerging market currencies, increasing the likelihood of large structural adjustments against the US dollar.
• The resolution criteria relies on the single maximum absolute change among ten countries. Having ten distinct chances at a severe currency swing greatly increases the mathematical probability of a high outcome.

Strongest Arguments for Lower Values

• Extreme swings, such as the 40 percentage point move seen in Argentina in 2024, are usually the result of one-off, historic policy shifts (like major immediate devaluations) that are unlikely to be repeated to the same degree in the current window.
• Historical precedents for normal volatility within this exact January to July timeframe yield more modest maximum changes, such as 8.1 points in 2021 (Colombia) or 12.5 points in 2023 (Egypt).
• Several of the tracked currencies, such as the Mexican Peso or Brazilian Real, generally operate within well-established bounds, typically fluctuating by a milder 5 to 15 percentage points over six months.
• Many of these emerging markets have already undergone massive devaluations in recent years, meaning their currencies might now be closer to their true purchasing-power parity baselines, reducing the scale of future corrections.

Key Uncertainties

• Trajectory of Argentina’s Monetary Policy: The success or failure of Argentina’s newly instituted floating-band regime will be the single largest determinant of tail-end volatility.
• Central Bank Interventions: Unexpected capital controls or heavy foreign exchange market interventions in Turkey or Egypt could artificially suppress valuation changes or trigger massive snap-back devaluations if controls are abruptly abandoned.
• US Dollar Strength: Because the index measures valuations against the US dollar, an unexpected surge or collapse in broader US dollar strength due to Federal Reserve rate changes would shift the entire board, potentially amplifying the maximum change.
• Emerging Market Tariffs: The scale and enforcement of potential 2026 trade policies remain unclear, and severe implementations could trigger disproportionate capital flight from countries like Mexico or Brazil.