Michael Burry became famous for predicting the United States housing crash in 2008.
His story appears in the book and movie “The Big Short.” Actor Christian Bale played him in the film.
Burry’s fund, Scion Asset Management, bought put options. A put option is a bet that a share price will go down.
He spent about 188 million dollars on puts against Nvidia and 912 million dollars on puts against Palantir.
Tech and AI shares have risen very fast this year. Some experts think the prices are too high.
Burry wrote on social media that sometimes he sees bubbles, and sometimes the best move is not to play.
After his post, the Nasdaq Composite fell about 2%, and the S&P 500 also dropped.
Some analysts say a small pullback in tech stocks is normal after big gains.
Palantir’s chief executive, Alex Karp, called people who bet against his company “crazy” and said it motivates them to do even better.
Even after the recent fall, shares of both Nvidia and Palantir are still much higher than at the start of the year.