SoundHound AI stock jumped 11.7% to $12.71 after Vanguard revealed a 10.1% stake, sparking a surge in retail optimism. Message volume spiked 200% as traders speculated on further upside, despite analysts' average price target of $11.81, implying a 7% downside. Sentiment on Stocktwits hit a 1-year high at 93/100, 'extremely bullish.'