Why China's A-Share Selloff Accelerated: A Four-Factor Resonance — and a Full-Chain Profit Map of the AI Trade

From late June to October 22, 2026, China's A-shares went through a decline that was deep in magnitude and accelerating at the end: the CSI 300 fell 20.2% from its high into a technical bear market, while the ChiNext Index and the STAR 50 both retraced more than 40%. This article argues that the selloff was not the product of any single piece of bad news, but of four factors resonating together — an external shock in rates and oil as the trigger, the unwinding of the crowded AI trade as the root, passive deleveraging by leveraged and institutional money as the amplifier, and fading stimulus hopes with no incremental buyers as the missing floor. The four interlock; remove any one of them and the drops of October 15 and October 22 cannot be explained. Star ratings throughout give a rough indication of how firm each factor stands; sources are listed at the end. Data as of the close on October 22, 2026. This record contains the English edition (with the original Chinese text as an appendix) and the full Chinese edition.Research and drafting were assisted by AI. All analysis, judgments, and the final text are the author's own.