美股还会跌多久？历史数据看，大涨后抛售潮平均持续25个交易日，当前已经21天了

Core Viewpoint - Morgan Stanley's latest analysis suggests that the current sell-off may be in its "latter half," but the most vulnerable speculative areas of the market still face further "de-bubbling" risks, indicating a pessimistic short-term outlook [1] Group 1: Market Trends - Since peaking on October 15, the momentum index composed of long and short strategies has declined by over 14% [2] - The current sell-off, led by strong stocks, has lasted for 21 trading days, approaching the historical average duration of about 25 trading days [4] - The depth of the current momentum stock sell-off, with a 19% decline since the peak, aligns closely with the historical average drop of -22% during similar sell-offs [8] Group 2: Investor Positioning - Both hedge funds and retail investors have highly concentrated positions, increasing market risk. Hedge funds' long leverage levels are at the 98th percentile over the past five years, nearing peaks not seen since 2006 [11] - Despite recent selling in popular sectors like AI and technology, hedge funds' overall risk exposure has not significantly decreased, with net exposure in momentum stocks still at the 79th percentile over the past year [15] - Retail investors' holdings overlap significantly with hedge funds, indicating a concentration in crowded sectors [21] Group 3: Retail Investor Behavior - Retail fund flows are becoming a key factor affecting market structure, with nearly half of retail buying concentrated in the top ten companies, including Nvidia (NVDA), Tesla (TSLA), Palantir (PLTR), and Meta [23] - This shift means that funds flowing into smaller, unprofitable speculative stocks are decreasing, impacting the performance of the "retail favorites" portfolio, which has underperformed the Nasdaq 100 by about 15% since October 15 [25] Group 4: Technical Risks - Two technical factors are amplifying market vulnerability: the unprecedented "crowding risk" with 45 stocks appearing in multiple momentum portfolios, historically leading to further declines in the following months [27] - The structure of the options market poses additional risks, as the growth of leveraged ETFs has shifted the market's gamma exposure to net short, making the market more susceptible to severe intraday fluctuations [29]