[Google Stock Surge Drives U.S. Market Rebound, Experts Warn Holiday Trading May Increase Volatility] Google's stock closed up more than 6% on Monday, leading a broad rally in U.S. markets. Investors have turned optimistic about Google's positioning in the artificial intelligence competition after the company released its upgraded AI model, Gemini 3, last week. Melissa Brown, Managing Director of Decision Research at SimCorp, stated that a single stock driving market gains may not necessarily reflect an improvement in market fundamentals and is unlikely to serve as a sustained driver for growth. Holiday trading volume is expected to be light, and with no major catalysts ahead of the Federal Reserve's December policy meeting, market volatility could increase. Brown noted that if the upcoming September retail sales and Producer Price Index data signal a 'stagflation environment,' it could trigger further volatility.