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

Question

Six frontier AI models put this at 37% by 2 Oct 2029. Full reasoning from every model.

WillHappen.ai · Accepted Answer

37% — the median of 6 frontier models, resolving by 2029-10-02.

Answer

Gemini (Google): 42% — A full 20% bear market depends on an unexpected US recession or a burst in mega-cap tech valuations over the next 15 months. Historical US data shows 20% bear markets hit roughly once every six years, yielding a baseline ~25% risk across 15 months. Elevated cyclically adjusted P/E multiples and concentrated equity leadership increase vulnerability to sudden shocks above baseline. Substantial Federal Reserve rate cuts combined with steady corporate earnings growth would prevent any severe drawdown.

Answer

Claude (Anthropic): 68% — Whether a recession, credit event, or valuation reset hits within a 3+ year window, which historically happens often. Base rate: 20% drawdowns occur roughly every 3-5 years historically, and this window spans over 3 years to late 2027. Current elevated valuations (high CAPE, concentrated mega-cap tech weighting) raise vulnerability to a sharp correction or bubble unwind. Main offsetting factor is continued Fed easing and resilient earnings/AI capex cycle, which could extend the bull run without a 20% dip.

Answer

GPT (OpenAI): 78% — A 20% drawdown is common over a roughly three-year horizon, even without a recession forecast. The index has had many 20% peak-to-trough bear markets since 1929; multi-year windows capture a large share of them. A recession, credit shock, inflation resurgence, or valuation reset could produce the decline before December 2027. I would lower this materially if earnings growth stays broad, inflation remains contained, and policy easing avoids a recession.

Answer

Grok (xAI): 28% — Whether a classic 20% peak-to-trough bear materializes in the remaining 15 months. Fed, earnings, and recession timing must produce a 20% slide by 31 Dec 2027; no single actor controls it. Post-1950 bears occur ~once every 5–6 years, implying ~22% Poisson chance in 1.25 y; elevated valuations lift it modestly. A sharp 2026 Q4–2027 H1 recession print or credit event would raise the odds most.

Answer

DeepSeek (DeepSeek): 22% — A 20% S&P drawdown needs a catalyst — recession, credit event, or policy shock — and none is currently forcing one. Since 1950, a 20%+ decline has occurred roughly once every 6-7 years, so a ~3-year window carries a base rate near 30-35%. The Fed, not the calendar, decides: cuts in 2026-27 would cushion equity downside, while a hawkish hold into a slowing labor market raises it. The 2025 AI-capex boom and elevated valuations make the index fragile, but fragility alone hasn't triggered a bear market without an earnings or credit break.

Answer

Qwen (Alibaba): 31% — This hinges on whether a recession or credit event hits within ~27 months, not on whether valuations are stretched. Base rate: S&P 500 has experienced a ≥20% drawdown roughly once every 7–8 years; a 27-month window gives ~30% base probability. Current valuations are elevated and the cycle is mature, but no recession signal (inverted yield curve has normalized, unemployment still low) is flashing yet. A single Fed policy error or geopolitical shock (e.g., oil spike, trade war escalation) would push this above 50%; absent that, mean reversion alone rarely triggers a…

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

The S&P 500 experiences a single-day decline of at least 7% before the end of 2027.

The Federal Reserve raises its 2026 core PCE inflation projection at its next Summary of Economic Projections.

The upcoming U.S. headline PCE inflation reading meets or exceeds 3.7% year over year.

The next Euro-area composite PMI release remains at or above 53.1.