BlockBeats news, October 14 — Scott Rubner, Head of Equity and Derivatives Strategy at Citadel Securities, noted in his latest research report that retail investors net bought $9.1 billion in US stocks through the platform last week, the largest single-week net buying on record in nearly 15 years, with funds mainly flowing into AI-related stocks and ETFs.Among them, semiconductor stocks saw net buying of approximately $2.6 billion, while AI infrastructure-related stocks saw net buying of approximately $2.4 billion. Rubner stated that this round of buying reflects strengthened directional bets by retail investors rather than an overall rise in trading activity: retail buy volume exceeded sell volume by 2.7%, with the directional skew at roughly the 90th percentile over the past year, while overall trading activity was only at the 42nd percentile.Previously, Rubner had judged that retail funds would re-enter the market in October. The latest data also shows that despite lingering concerns about an AI bubble, retail investors are still concentrating on adding positions in AI and semiconductor sectors.