The S&P 500 drops at least 20% from its peak before the end of 2027.

Question

Six frontier AI models put this at 34% by 15 Sept 2029. Full reasoning from every model.

WillHappen.ai · Accepted Answer

34% — the median of 6 frontier models, resolving by 2029-09-15.

Answer

Gemini (Google): 37% — A bear market requires a sharp macro shock or recession over the 15-month window ending December 2027. Historically, S&P 500 bear markets occur roughly once every 6 to 7 years, giving a baseline 15-month probability near 20-25%. Stretched equity valuations leave the index vulnerable, but Fed rate-cutting cycles typically provide liquidity support. A formal US recession call by the NBER or an uncontained credit event would push odds above 60%.

Answer

Claude (Anthropic): 48% — Whether a recession, AI-valuation unwind, or geopolitical shock triggers a 20%+ drawdown before end-2027. Base rate: bear markets of 20%+ occur roughly once every 4-6 years historically, and this window spans over a year across elevated valuations. Current market has high concentration risk in AI/tech megacaps, stretched valuations, and rate uncertainty, raising odds above a calm-period baseline. A resolution to soft-land the economy with continued earnings growth and Fed easing could keep markets grinding higher without a correction of that magnitude.

Answer

GPT (OpenAI): 63% — A 20% drawdown is common over a three-year horizon, but the timing hinges on recession and valuation shocks. The index has suffered 20% peak-to-trough declines in several recent cycles, including 2000–02, 2008–09, 2020 and 2022. Between now and 31 December 2027, a recession, earnings reset or credit event would need to outweigh continued AI-led profit growth and easing policy. I would raise this sharply if US unemployment rose above 5% or credit spreads widened materially during 2027.

Answer

Grok (xAI): 31% — A 20% S&P drawdown by end-2027 turns on a recession or policy shock arriving inside the next 15 months. Fed, Congress and corporate earnings must keep the expansion intact through Dec 2027; any 2027 NBER recession call would trigger it. Bears historically arrive ~every 5 years (13 since 1950), so a 15-month window has ~25% base rate; elevated valuations lift it a few points. A sudden 2026-H2 credit event or 75 bp unexpected hike would most change the odds.

Answer

DeepSeek (DeepSeek): 22% — A 20% drawdown needs a trigger — credit stress or a recession — and none is currently priced or scheduled. Since 1950, the S&P has entered a 20%+ bear market roughly once every 6-7 years, giving a ~25-30% base rate for any 3-year window. The Fed is easing into a soft-landing backdrop, and no major bank or credit market is flashing the stress that preceded 2000, 2008, or 2020. The single development that would most change this: a sharp spike in high-yield credit spreads or a rapid unemployment rise above 4.5%.

Answer

Qwen (Alibaba): 31% — A 20%+ peak-to-trough drawdown within ~15 months requires a recession or major shock; base rate is roughly once per decade. Since 1950, the S&P 500 has experienced a 20%+ drawdown roughly 11 times over 75 years, implying ~15% annual probability; a 15-month window raises this to ~18-20%. Current valuations (forward P/E ~21-22x) are elevated, which historically correlates with larger drawdowns when shocks hit, nudging the probability above base rate. The key variable is whether a recession materializes or a geopolitical/financial shock lands; absent a clear catalyst now, I sit modestly above the unconditional base…

The S&P 500 drops at least 20% from its peak before the end of 2027.

The next reported weekly figure for India's foreign exchange reserves exceeds $785.7 billion.

The next official UK CPI release shows annual inflation higher than 3.1%.

The Bank of Japan raises its benchmark interest rate at its next policy meeting.

The Bank of England increases the Bank Rate at its next Monetary Policy Committee meeting.