STORY: :: Lisa Bernhard, Reuters:: Sam Stovall, Chief Investment Strategist, CFRA ResearchNvidia hit a market value of $3.92 trillion on Thursday, briefly putting it on track to become the most valuable company in history, as Wall Street doubled down on optimism about AI."When you look to other companies in the past that were the most valuable, whether it's IBM or Exxon, you have to say the only place they can go is down," said Stovall.But Nvidia's market cap milestone "shows that time has moved on, that inflation, that prices have increased," he explained. "And it also shows the importance of tech in general and AI in particular."Speaking with Reuters' Lisa Bernhard, Stovall added that the AI trade should help propel the S&P 500 and Nasdaq for the "next several months."...