[Citadel Securities: Retail Investors Net Bought $9.1 Billion in U.S. Stocks Last Week, AI Chip Stocks Became the Main Investment Focus] According to Bloomberg, despite ongoing concerns about an AI bubble, the Nasdaq 100 Index and the S&P 500 Index both reached record highs last week. Scott Rubner, Head of Equities and Derivatives Strategy at Citadel Securities, revealed that retail investors net bought $9.1 billion in U.S. stocks on the platform last week, marking the largest weekly net purchase in the past 15 weeks. The funds primarily flowed into AI-related stocks and ETFs. Among these, retail investors net bought $2.6 billion in semiconductor stocks last week, the third-highest weekly net purchase in the past year, driving October's semiconductor stock net purchases to potentially set a record-high monthly figure on the platform. Additionally, retail investors purchased approximately $2.4 billion in AI infrastructure-related stocks.