Warren Buffett’s company placed a rare bet on a technology company late last year and it has already paid off in a big way.

Berkshire Hathaway revealed in documents filed with regulators on Monday that it bought near 15 million shares in game publisher Activision Blizzard during the last three months of 2021.

The purchase came not long before Microsoft’s announcement in January that it was acquiring Activision for $68.7 billion, sending the stock soaring. Activision’s shares are up 22.5% so far this year.

Berkshire estimated that its 14.7 million shares in Activision Blizzard, the maker of Candy Crush and Call of Duty, were worth roughly $975 million at the end of 2021. At the close of trading Monday, they were worth $1.19 billion.

The investment by Buffett’s firm was a surprising move by the famously tech-averse investor. Buffett has long avoided investing in tech companies because he says it is too hard for him to pick the long-time winners in that sector.

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The other changes to Berkshire’s roughly $330 billion portfolio revealed Monday were more typical for Buffett, such as increasing an investment in oil giant Chevron, eliminating a stake in Teva Pharmaceuticals and trimming its investments in several other drugmakers.

Buffett and other Berkshire officials don’t comment on these quarterly stock filings, and the reports don’t state whether either one of Berkshire’s two other investment managers made the moves. Buffett typically handles all the company’s larger investments worth more than $1 billion apiece such as its major stakes in Apple, Bank of America and Coca-Cola, so the size of the Activision Blizzard investment suggests Buffett made that decision.

Berkshire continued rebuilding its Chevron investment in the fourth quarter when it picked up nearly 10 million shares, but the stake of 38.2 million shares remains smaller than the 48.5 million shares it held when it first revealed the investment a year ago. Berkshire sold off a large chunk of its Chevron investment in the first half of last year.

Buffett’s firm sold off the 42.8 million Teva shares it held and trimmed its holdings in other pharmaceutical companies Bristol Myers Squibb, Abbvie and Royalty Pharma.

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Berkshire also eliminated a $266 million investment in Sirius XM during the quarter.

It revealed a new investment in Brazilian fintech NU Holdings that went public in December. Buffett’s company held 107 million shares of NU Holdings at the end of the year.

In other moves, Berkshire cut down its investment in professional services firm Marsh & McLennan and trimmed its holdings in Mastercard, Visa and Charter Communications.

Besides investments, Berkshire owns more than 90 companies outright, including Geico insurance, BNSF railroad, and several major utilities. The conglomerate also owns manufacturing, furniture, shoe, jewelry, chocolate, underwear and brick companies.