Nomura Holdings Inc., the nation's largest investment bank, said Friday it generated a ¥21 billion profit from selling its stake in U.S. asset manager Fortress Investment Group LLC.

Nomura will include the gains in its results for the fourth quarter ending March 31, spokesman Kenji Yamashita said Friday. The company sold a 12 percent stake in Fortress on Thursday for $363.4 million.

The one-time gain may bolster earnings at Nomura, which bought the stake seven years ago, and help offset a potential slump in trading revenue and brokerage commissions if the Tokyo Stock Exchange tails off. The Nikkei stock average has slid 11 percent this year, the worst performer among developed markets.

Fortress, the first publicly traded alternative-asset manager in the United States, repurchased the 12 percent stake for $6 a share, according to a statement Thursday from the New York-based firm.

The stock is still below the $18.50 at which Fortress sold shares to the public in 2007.

Nomura's profit may drop to ¥53 billion in the quarter ending March from ¥82.4 billion a year earlier, according to the average of eight analyst estimates compiled by Bloomberg last month.

The brokerage bought a 15 percent stake in Fortress in December 2006 for $888 million, paying $16.12 a share to the company's principal executives, who included co-founders Wes Edens, Bob Kauffman and Randy Nardone, as well as partners Pete Briger and Michael Novogratz.

Fortress, which oversees $58 billion in hedge funds, credit assets and private-equity funds, plummeted in the years after its IPO, reaching a low of 95 cents in December 2008.

The stock on Thursday rose 6 percent, the most since April 2013, to close at $8.47 in New York trading.

Nomura helped Fortress raise its two Japan Opportunity Funds, which invest in distressed real estate loans and other troubled assets. Fortress's second Japan fund closed in 2012 with $1.65 billion, following a 2010 pool that raised $800 million.