中国上证综指8月19日（周三）开盘下跌38.18点，跌幅：0.96%，报3952.12点； 中国深证成指8月19日（周三）开盘下跌305.52点，跌幅：2.09%，报14316.98点； 中国沪深300指数8月19日（周三）开盘下跌65.76点，跌幅：1.39%，报4660.06点； 中国创业板指数8月19日（周三）开盘下跌100.05点，跌幅：2.7%，报3605.52点； 中国科创50指数8月19日（周三）开盘下跌51.96点，跌幅：2.9%，报1738.91点。

卡塔尔外交部发言人：伊朗与卡塔尔在伊朗飞行员问题上保持直接联系。

Goldman Sachs TMT trading desk says weekly implied US equity volatility is about 89bp, near a five-year low, with its panic reading at 0.36/10. The desk estimates option market makers hold roughly $15bn of positive-gamma hedges, near the 99th percentile, which biases dealers to sell into rallies and buy into dips and thus mutes short-term moves. It also estimates 96% of S&P 500 firms are in open repurchase windows and announced buyback authorizations exceed $1trln, implying corporate repurchases could absorb selling in summer’s thin liquidity. Macro risks remain—long-end yields are still rising and oil has resumed an uptrend—but derivatives markets are pricing very low near-term volatility. If dealer positive gamma and buybacks persist, US equity short-term volatility may stay suppressed; if those supports weaken, the current ultra-low vol will increase sensitivity to price re-expansion.