The US bull market continues with the S&P 500 closing higher in 2027 than in 2026.

Question

Six frontier AI models put this at 65% by 3 Nov 2029. Full reasoning from every model.

WillHappen.ai · Accepted Answer

65% — the median of 6 frontier models, resolving by 2029-11-03.

Answer

Gemini (Google): 68% — Historically, the S&P 500 delivers positive annual returns roughly seven out of every ten years, even during extended expansions. S&P 500 annual returns are positive in roughly 73% of calendar years historically, providing a resilient baseline. Elevated valuations after years of bull market gains increase vulnerability to recessions, shaving several points off base rates. A sharper-than-expected Fed tightening cycle or an unexpected US recession by mid-2027 would rapidly flip this probability downward.

Answer

Claude (Anthropic): 58% — Historically the S&P rises in roughly 65-70% of years, but 2027 sits deep into an aging multi-year bull run. Base rate for any given year's S&P return being positive is ~65-70% historically, modestly favoring a yes. Market would need no major recession, rate shock, or geopolitical/AI-bubble correction through 2027; valuations are already elevated heading in. A sharp 2026 rally that overextends valuations increases downside risk for 2027, pulling this slightly below the historical base rate.

Answer

GPT (OpenAI): 62% — It chiefly turns on whether earnings growth and Fed policy avert a recessionary bear market during 2027. Since 1928, the S&P 500 has posted consecutive positive calendar years more often than not after an up year. The index must finish 2026 higher and then close 2027 above its 2026 year-end level; no vote or formal approval is needed. A sharp 2027 recession, inflation rebound forcing rate hikes, or credit event would materially lower the odds.

Answer

Grok (xAI): 72% — S&P 500 2027 year-end close exceeds 2026 close. Positive calendar years occur ~73% of the time since 1928; 2027 is a post-midterm year whose average return sits well above that base. No 2026 recession signal yet forces a 2027 contraction; the Fed and earnings would have to reverse first. A sharp 2026 Q4 sell-off or 2027 policy shock would most change the odds.

Answer

DeepSeek (DeepSeek): 62% — Whether the S&P 500's 2027 close beats 2026's hinges on Fed easing and AI-capex earnings holding through next year. Base rate: since 1950, the S&P has risen in roughly 70-75% of individual calendar years, so a single up-year is the default. This case sits below that: after 2023-2026 gains, valuations are stretched and the index is entering 2027 with less cushion than a typical year. The Fed's path matters most — if rate cuts stall or AI capex disappoints, a 2027 down year becomes likely; a soft landing keeps the streak alive.

Answer

Qwen (Alibaba): 74% — This is essentially asking whether 2027 is a positive S&P year; base rate ~75%, bull-market context nudges it up slightly. The S&P 500 posts positive calendar-year returns ~75% of the time; during confirmed bull markets the conditional rate rises to ~80%, but we can't confirm how extended… The main downside scenario is a recession or exogenous shock hitting in 2027—historically recessions arrive roughly once per 8-10 years, and the last one was 2020, so… A development that would move this sharply: Fed signaling a tightening cycle or a credit event emerging in H1 2027 would cut the probability toward 50.

The US bull market continues with the S&P 500 closing higher in 2027 than in 2026.

The S&P 500 declines by at least 20 percent from its recent high before mid-2027.

The S&P 500 remains in a technical bear market through the end of 2026.

US equity markets transition to 24-hour weekday trading before 2028.

Major US stock exchanges experience an unscheduled trading halt or delay before December 2026.