AllianceBernstein Holding LP became another victim of the hedge fund rout when American International Group Inc. decided to wind down a six-year relationship with the asset manager.

AIG was the “most significant” driver of outflows last month as the company withdrew about $6 billion, AllianceBernstein said Tuesday in a statement. The insurer previously pulled $1.1 billion.

“The fact that AIG took it in-house was a little bit surprising,” Surinder Thind, an analyst at Jefferies Group, said by phone. “But given the trend that hedge funds are generally struggling, for AIG to manage its own exposure is not unreasonable.”

AIG Chief Investment Officer Doug Dachille is working to reduce fees and limit AIG’s reliance on third-party asset managers after joining last year to oversee a $350 billion investment portfolio dominated by bonds. The company said in January that it planned to free up capital by scaling back hedge-fund holdings. The investments being pulled from AllianceBernstein’s oversight may remain in hedge funds, with AIG gaining more control over allocations, according to a person familiar with the matter who asked not to be identified discussing the insurer’s strategy.

2010 Deal

The relationship dates to 2010 when Alliance Bernstein Chief Executive Officer Peter Kraus struck a deal with AIG’s SunAmerica division to acquire a business that manages private-equity and hedge fund holdings, including assets that back obligations to policyholders. AIG was selling units at the time to simplify the insurer and help repay a U.S. bailout, and Kraus agreed to pay $14.3 million in cash and make additional revenue-sharing payments, according to a 2011 regulatory filing.

AllianceBernstein said in July that AIG would redeem $7 billion through the third quarter.

“The revenue impact, though, is negligible,” Kraus said in a conference call that month. “It’s a very low fee.” His company reported institutional outflows in four months this year, two of which were tied to AIG.

“That’s always the risk with institutional money,” Greggory Warren, an analyst with Morningstar Inc., said by phone. “It’s lumpy. It comes in large amounts and it leaves in large amounts.”

AllianceBernstein also has retail and private-wealth channels and oversaw about $490 billion as of Sept. 30, down from $496 billion a month earlier. The company’s stock has slipped 8.1 percent this year as of 1:20 p.m. in New York.

Before joining AllianceBernstein in 2008, Kraus was an investment banker at Goldman Sachs Group Inc., which counted AIG as a client. Jon Diat, a spokesman for AIG, didn’t immediately return a message seeking comment.