BlackRock Inc., the world’s largest money manager, and EvanGreenberg’s ACE Ltd. are forming a reinsurance venture that is seeking to raise $800 million to $1.3 billion.

The business is named ABR Reinsurance Capital Holdings Ltd. and is based in Bermuda, according to a regulatory filing Thursday from the company.

Money managers are pushing into reinsurance to expand the pool of funds that they oversee and to diversify into investments that aren’t correlated with stock or bond markets. While primary carriers often turn to reinsurers to share the largest risks, Greenberg has said Wall Street offers an alternative partner.

“I can envision a day when we aren’t simply accessing traditional reinsurers, but originating risk globally that we package and distribute directly through the capital markets,” Greenbergwrote in ACE’s annual report last year.

Citigroup Inc., Deutsche Bank AG and Morgan Stanley are listed as banks for the offering. Jeffrey Zack, a spokesman for ACE, declined to comment, as did BlackRock’s Brian Beades.

BlackRock has handled investments for Zurich-based ACE subsidiaries. The money manager oversaw about 22 percent of the insurer’s investment assets, according to a regulatory filing last year.

Head Patting

Insurance executives who may have thought of Wall Street firms as competitors have begun to work with them. Mike McGavick, XL Group plc’s chief executive officer, said in a January conference call, that relationships between the industries had improved.

In the past, capital-markets partners would “pat you on the head and they’d say, ‘You just go kinda do some break-even underwriting for us,’” McGavick said. “As the year went on, it was very clear that the smart players in those alternative capital spaces started saying, ‘You know, actually underwriting matters too.’’