US chip stocks plunge 16% in longest losing streak since 2008

US chip stocks just had the kind of stretch that makes portfolio managers check their blood pressure. The Philadelphia Semiconductor Index, known on trading desks as the SOX, fell 16% over eight sessions. That marks its longest losing streak since October 2008. Eight days, 30 losers, one very bad Friday The slide began on October 6 and ran through mid-October 2026. It ended with a particularly ugly session around October 16-17, when the index dropped 3.83% to close at 11,137.29. On that final day, there was nowhere to hide. All 30 stocks in the index finished lower. Arm Holdings took one of the heavier hits, falling roughly 7%. Broadcom, Micron, AMD, Intel, Lam Research, and KLA each shed about 5%. The damage extended well beyond the index itself. More than $1 trillion in market capitalization was wiped out across AI and semiconductor stocks during the selloff. Short sellers reportedly booked an estimated $32 billion in gross paper gains over seven days, a window in which the index dropped more than 12%. The CoreWeave problem If the selloff had a canary, it was CoreWeave. The AI cloud provider saw its shares fall nearly 12% in a single session and lose about 25% over five sessions....