Warren Buffett says he made a mistake with Alphabet.

The Oracle of Omaha said he called on Berkshire Hathaway to invest billions in Alphabet. The conglomerate owns shares worth about $31 billion. Buffett’s only regret? That Berkshire did not invest in Google’s parent company before, he said in an interview with CNBC this week.

“I initiated it,” Buffett said, adding that he didn’t make any decisions that Greg Abel, his successor at Berkshire, didn’t approve of, and vice versa.

Alphabet shares rose nearly 4% on Wednesday, putting the tech titan up 17% so far this year.

Alphabet was Berkshire’s biggest stock purchase last quarter, and the company now represents 6% of its total portfolio. Google’s parent company is also Berkshire’s sixth-largest holding company, below Occidental, Chevron, Bank of America, Coca-Cola, American Express and Apple, which is Berkshire’s largest investment.

Aside from its stakes in Apple and Alphabet, Berkshire has rarely invested in technology, and Buffett previously said he avoided the sector because of its unpredictability. In the past, you characterized Apple as a consumer company.

The latest investment in Alphabet also reflects Buffett’s lasting influence over Berkshire despite officially stepping down as CEO last year.

Buffett noted how questions about AI capital spending now loom over Google and other tech giants in the artificial intelligence race. Investors have been concerned about the billions being spent on AI, as many companies have yet to monetize or see significant cost savings from the technology.

However, it appears that Alphabet is more likely than the others to emerge victorious, Buffett said.

“I made a mistake,” Buffett said of not investing in Alphabet sooner. “I think they are more likely to be winners based on their track record than probably 90% or 95% of what is being traded through Wall Street,” he added.

“They have no choice,” he added of companies’ AI capital spending plans. “Now they’re playing a game in many cases, or in some cases, where they’re playing a game that they don’t want to play.”

He added that he didn’t like Alphabet as much as four or five other companies Berkshire owned, but he didn’t specify which ones.