Michael Burry is in the headlines again, with the Big Short investor saying today’s market feels like the “last months of the 1999-2000 bubble”.Burry cites one analysis which found that the top 10 Nasdaq 100 companies are up 784 per cent over the past year, ahead of even the most frenetic phase of the 1990s boom. He also argues that today’s valuations are higher than they seem, with some key technology stock earnings being overstated. Critics sigh that we have seen multiple Burry warnings of market excess in recent years, and repeated calls for severe market dislocations that have not materialised.Burry rejects the perma-bear label, and points to correctly identifying turning points in 2000 and 2008, as well as calling 2021’s meme-stock mania (although who didn’t?) and 2023’s brief bank stock run.Many would agree that pockets of the market look stretched today. Semiconductors have seen extreme momentum, following what Bespoke Investment calls “one of the most epic runs in history”. Technology stocks in general have been on fire, with Bespoke noting the US technology sector gained more than 30 per cent in the 30 trading days that followed the Iran war low on March 30th.[ AI bubble? Big Short investor Michael Burry’s bold calls often miss the markOpens in new window ]However, the broader picture is less uniform. Earnings growth has been extremely strong – so strong, in fact, that valuation multiples in the technology sector have actually fallen. Investors are being discriminating, with companies that miss earnings being punished more severely than usual. Retail investor sentiment surveys are decidedly lukewarm, with not a hint of euphoria.Besides, momentum has an awkward tendency to persist. All too often, strong markets get much stronger.The difficulty, as ever, is timing. The difference between “I was early” and “I was wrong” is a subtle one, and often irrelevant to investors living through it. Does today’s market resemble 1999? Or is it more like 1997?For long-term investors, the least unsatisfactory answer may simply be to stay invested.