Core Viewpoint - Investors are preparing for the expiration of $6.5 trillion in nominal value U.S. options this Friday, which may lead to increased volatility in the stock market [1][4]. Group 1: Market Dynamics - The phenomenon known as "triple witching" occurs when multiple categories of derivative contracts expire simultaneously, which could result in sudden market fluctuations after the expiration date [1]. - Since early May, the U.S. stock market has experienced relatively mild intraday volatility, partly due to a "pinning effect" from a large number of put options established earlier in the year [1]. - The "pinning effect" refers to the tendency of stock prices to close near the strike prices of heavily traded options as expiration approaches, which has helped stabilize the market [1]. Group 2: Investor Behavior - In early April, many pessimistic investors bought hedging tools against market declines and financed these protective positions by selling call options slightly above the current level of the S&P 500 index (5981 points) [2]. - Market makers and brokers' actions to hedge their positions can significantly impact the stock market, contributing to overall market dynamics [2]. - The market is currently in a "positive gamma" state, where participants tend to sell on price increases and buy on declines, thus suppressing volatility [2]. Group 3: Special Significance of Upcoming Expiration - Research from Citigroup indicates that the upcoming triple witching day has "special significance," with an estimated $5.8 trillion in nominal outstanding equity options expiring, including $4.2 trillion in index options, $708 billion in U.S. ETF options, and $819 billion in individual stock options [3]. - The higher figure of approximately $6.5 trillion mentioned by Rocky Fishman includes the nominal value of index futures options, which will also expire on Friday [4].

智通财经APP获悉，投资者正为本周五即将到期的6.5万亿美元名义价值的美国期权做好准备，这可能 会让股市重新出现更大幅度的波动。 每个季度，多个不同类别的交易所衍生品合约会在同一天同时到期，这一现象在市场观察人士中被称 为"三巫日(triple witching)"。虽然市场并不预期周五当天就会出现剧烈波动，但这一天之后，股市可能 会重新面临突然波动的风险。 自5月初以来，美国股市的日内波动一直相对温和，这部分得益于年初大量建立的看跌期权交易所带来 的"钉仓效应"。所谓"钉仓效应(pinning)"，是指在期权到期日临近时，股价倾向于靠近成交量较大的期 权执行价附近收盘。在当时，标普500指数反弹至接近历史高点的可能性看起来非常渺茫。研究机构 Asym 500 LLC的创始人Rocky Fishman表示，这些交易帮助市场维持了稳定。 今年4月初，在关税引发市场剧烈波动之际，许多悲观的投资者买入了股市下跌的对冲工具，并通过在 标普500指数当前水平(5981点)稍上方卖出看涨期权，为这些保护性仓位融资。Rocky Fishman表示："过 去几个月我们一直在应对关税风波，当时很多人认为6000点这个水平难以触 ...