AI trio split on 2026 Japan market cap leader

2026-08-11

How far ahead can the latest artificial intelligence (AI) see? When asked which Japanese company would have the biggest market capitalisation at the end of 2026, ChatGPT from OpenAI named SoftBank Group (SBG). The answer will be checked at the end of 2026, along with predictions on politics and entertainment.

Testing AI forecast accuracy

In late July, Nikkei sent 10 questions in browser versions of ChatGPT, Google's Gemini and Anthropic's Claude. Only the question text was entered, leaving each AI to choose its own sources and criteria.

Three AIs, three different picks for market leader

Asked to predict the company with the largest domestic market value as of the close on Dec. 1, Gemini chose Mitsubishi UFJ Financial Group and Claude picked Toyota Motor. Including ChatGPT's SBG, the three AIs differed in their views.

ChatGPT cited expanding investment in AI infrastructure, Gemini pointed to an additional rate hike by the Bank of Japan, and Claude said that if the yen stays weak, foreign-exchange gains will support earnings. SBG plans to invest a cumulative $64.6 billion, or about 10 trillion yen, in OpenAI.

Stock prices and award winners also forecast

The three models also failed to agree on Japanese stocks, US stocks and the yen's exchange rate against the dollar. ChatGPT predicted the Nikkei average would rebound and top 70,000 in December. It said corporate earnings in Japan remained strong and a weak yen would help exporters. Claude, by contrast, saw the Nikkei at 63,000, below the 64,362 level at the end of July. It cited growing concern over an AI bubble and high forecast price-to-earnings ratios as downside factors. On the yen, all three AIs projected a range of 155-158 yen to the dollar.

When asked to name up to three Nobel Prize winners, usually announced in October, ChatGPT and Claude both named Peter Shor of the Massachusetts Institute of Technology as a candidate for the physics prize. He proposed an algorithm for quantum computers, and ChatGPT said recent physics prizes have tended to focus on quantum science.

Japanese award picks and mistakes

For Japanese candidates, Gemini predicted that former National Cerebral and Cardiovascular Center board member Kenji Kangawa would receive the physiology or medicine prize. It cited his receipt of the Clarivate Citation Laureates award in September 2025, seen as a stepping stone to the Nobel Prize.

The three models agreed on the Major League Baseball Most Valuable Player award. They predicted Los Angeles Dodgers star Shohei Ohtani would be selected for a fifth time. While ChatGPT and Claude were confident Ohtani would win, Gemini saw Cubs outfielder Pete Crow-Armstrong as his biggest rival.

There were also simple mistakes. When asked which singers or groups would make their debut at the 2026 Kōhaku Uta Gassen, ChatGPT and Gemini named 'HANA' and 'M!LK', both of which had already appeared in 2025. The AI was told they had already been featured and asked to name different groups.

Small changes in assumptions or wording alter AI answers and accuracy. On political and economic questions, each AI replied that its prediction was probabilistic and that uncertainty was high, urging users not to take the responses at face value. Even on short questions, all three tended to present a wide range of grounds, swing factors and related information. For future predictions where the right answer is not yet known, they could become a useful aid for humans.

Survey overview

ChatGPT used the free version as of July 31, Gemini used 'Gemini 3.5 Flash' and Claude used the browser version of 'Claude Sonnet 5'. Default settings, including reasoning mode, were left unchanged and 10 questions were entered. A follow-up article comparing the predictions with the actual results is planned for December.

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