美股从惊喜变惊吓，原因何在？

Core Viewpoint - The U.S. stock market experienced a dramatic reversal on November 20, 2025, influenced by Nvidia's strong earnings report and subsequent investor concerns about tech stock valuations and interest rate expectations [1][4][15]. Group 1: Market Performance - The Nasdaq index opened high, rising 2.18% to a peak of 23,147.33 points, but ultimately closed down 2.15%, a drop of 486.18 points, ending at 22,087.05 points [1]. - The Dow Jones Industrial Average and S&P 500 exhibited similar single-day movements, reflecting overall market sentiment [3]. - The VIX index, a measure of market volatility, surged 11.67% to 26.42 points, marking a 32.10% increase over the past five days [3]. Group 2: Factors Influencing Market Reversal - Concerns over tech stock valuations arose after Nvidia's third-quarter revenue and profit exceeded expectations, leading to fears that the positive news was fully priced in and that growth may have peaked [6]. - The release of mixed U.S. non-farm payroll data showed an increase of 119,000 jobs, significantly above the forecast of 52,000, but the unemployment rate rose to 4.4%, higher than the expected 4.3% [7]. - The market's expectations for interest rate cuts diminished, with the probability of a 25 basis point cut in December dropping from 50.1% to 35.5% [7]. Group 3: Impact on Tech Stocks - The decline in interest rate expectations negatively affected tech stocks reliant on cheap capital, leading to significant sell-offs, including Oracle's stock, which fell 6.58% [9]. - Concerns about private credit risks and potential asset valuation vulnerabilities in the financial system contributed to a broader market sell-off [10]. - Bitcoin prices continued to decline, further correlating with tech stock performance, as leveraged trading in Bitcoin exacerbated selling pressure on high-valuation tech stocks [11]. Group 4: Trading Dynamics - Programmatic trading strategies, particularly from CTA funds, amplified market volatility as they triggered further sell-offs when market thresholds were breached [12]. - The options market, particularly zero-day-to-expiration options, played a role in exacerbating market movements, as market makers adjusted positions to hedge risks, leading to concentrated selling pressure [13]. - The "iron condor" strategy in options trading was identified as a factor suppressing market rebounds, as it required market makers to sell stocks to manage risk exposure [13]. Group 5: Future Outlook - The uncertainty surrounding Federal Reserve monetary policy and reduced investor interest in high-risk assets suggest that global markets, particularly U.S. stocks, may continue to face downward pressure [15]. - This environment may present opportunities for long-term investors to identify value amidst market volatility [15].