Shares of Google parent Alphabet plunged as much as 13% on Thursday after the technology giant missed Wall Street's third-quarter earnings expectations, with slowing growth in its core search advertising business and mounting artificial intelligence spending raising concerns among investors.Alphabet shares fell 13.4% during US trading, wiping out hundreds of billions of dollars in market value and putting the stock on course for one of its steepest single-day declines.US MarketsPowered ByAs on 29 Oct 2026, 07:58 PM ISTS&P 500 Top GainersTextron87.88(12.21%)Norwegian Cruise Line17.83(11.02%)Gen Digital26.97(10.74%)Huntington Ingalls Indus302.55(8.34%)Gainers»S&P 500 Top LosersServiceNow113.20(-24.60%)Fortinet138.85(-20.24%)Alphabet285.49(-12.13%)Alphabet283.52(-11.92%)Losers»The selloff came after the company reported a 25% year-on-year decline in net profit to $26.17 billion for the July-September quarter, compared with $34.98 billion in the corresponding period last year.