Tech stocks tumble for a second day. Here's what is behind the selloff.

Big tech stocks like Nvidia and Alphabet experienced a second consecutive day of declines as investors, once enthusiastic about AI investments, are now demanding more proof of substantial returns from these technologies. This shift reflects a broader trend where Wall Street's focus has moved from initial excitement to scrutinizing the financial benefits of AI. The selloff signals a potential change in investor sentiment, highlighting the pressure on tech companies to deliver on their AI promises or face market backlash.