Billionaire David Tepper Sold Micron and Sandisk, and Is Hedging Against 1 of Their Largest Customers

David Tepper is one of the greatest hedge fund managers of all time. He started Appaloosa Management in 1993 and went on to produce annualized returns of about 25% through mid-2019, at which point he had returned most of his outside investors' money.

Tepper has continued to produce excellent returns, now mostly managing his own money, taking concentrated and often contrarian positions to drive results. Appaloosa generated a massive 32% gross return in the first half of 2026 alone.

Missed Nvidia in 2009? This Rare Signal Is Flashing Again. In 2009, a "Double Down" signal flashed for a little-known chipmaker called Nvidia. For the first time in years, that same "Total Conviction" signal is flashing for a company 1/100th the size of Nvidia. Continue »

So, it's worth paying attention to the moves Tepper's making -- and you can, because he, like everyone who manages more than $100 million in assets, is required to disclose his fund's end-of-quarter holdings via a Form 13F four times a year.

Appaloosa's 13F for the second quarter (filed on schedule about 45 days after that period ended) showed that during the quarter, he sold two of the hottest stocks in the market: Micron (NASDAQ: MU) and Sandisk (NASDAQ: SNDK). Not only that, but he also bought put options (the right to sell shares at a set price within a preset period) on one of their biggest customers, which may suggest he sees something the market doesn't.

Tepper has been an investor in Micron for years, establishing a position in late 2016 and holding the memory-chip maker's stock through multiple earnings cycles. It's been his portfolio's largest single holding on multiple occasions. He made a big bet on the stock in the fourth quarter, adding 1 million shares to his position and call options controlling an additional 250,000 shares. He added even more shares in the first quarter. But after the huge run-up in the stock price, he cut his stake by 41% last quarter.

It's worth noting that Micron remained the second-largest position in the portfolio at the end of the quarter -- about 15% of Appaloosa's publicly traded equity portfolio. That said, the stock has accounted for up to 29% of Tepper's portfolio in the past. This suggests that he sees better investment opportunities now, or at least, sees the need to diversify away from memory-chip makers.

That sentiment is bolstered by the fact that he completely disposed of Appaloosa's position in Sandisk. That stake was 3% of the portfolio at the end of the first quarter, but disappeared in the second-quarter filing.