Warren Buffett’s Berkshire Hathaway Inc. asked the Federal Reserve to allow it to hold as much as 24.99 percent of American Express Co., a stake that’s been growing because of the lender’s stock repurchases.

“This is an application to continue to retain American Express stock, not to buy additional shares,” Marina Norville, a spokeswoman for New York-based AmEx, said in an emailed statement.

Berkshire applied to “increase the percentage ownership cap to 24.99 percent from the current 17 percent as a result of our share-repurchase program,” she said.

AmEx has recently returned “significant amounts of capital to shareholders” through dividends and buybacks, Chief Financial Officer Jeffrey Campbell said on a conference call with analysts last month. The company received approval to repurchase $4.4 billion of its shares during 2016 and an additional $1.7 billion in the first half of 2017, according to a statement last June.

Berkshire, American Express’s biggest shareholder, owned about 151.6 million shares, or 17 percent of AmEx’s stock, as of March 31, according to data compiled by Bloomberg. The stake was valued at $11.6 billion based on Thursday’s closing price. AmEx shares rose 0.7 percent to $76.88 at 10:30 a.m. in New York.

Wells Fargo

Berkshire disclosed its request to the Federal Reserve in a legal notice in the New York Daily News on Friday.

U.S. regulations have long limited ties between non-financial companies and banks. Investors typically have to tell the Fed and the public before acquiring ownership stakes that exceed certain levels, though that notice can be delayed if the threshold is reached because of share repurchases. In the 1990s, Buffett committed to be a passive shareholder at American Express after Berkshire’s stake exceeded 10 percent.

He applied to the Federal Reserve last year to expand his firm’s stake in Wells Fargo & Co. after the lender repurchased shares, increasing Berkshire’s ownership of the San Francisco-based bank above a regulatory threshold.

The billionaire investor agreed in April to cut his stake in the lender below the 10 percent level after regulators told Berkshire that remaining above it would limit the firm’s ability to do business with the bank. Buffett’s Omaha, Nebraska-based company said it sold or had plans to divest a total of 9 million shares.