NEW YORK (Bloomberg) — Assured Guaranty Ltd., the bond insurer backed by billionaire Wilbur Ross, posted its second net profit in seven quarters as it increased its market share and benefited from a new accounting standard.

First-quarter net income of $85.5 million, or 93 cents a share, compared with a loss of $169.2 million, or $2.09 cents a share, a year earlier, the Bermuda-based company said yesterday in a statement. After adjustments, Assured said its profit was 69 cents a share; the average estimate of eight analysts surveyed by Bloomberg was for profit of 15 cents.

The company has benefited from a jump in its market share as ratings firms and issuers deem competitors including MBIA Inc. and Ambac Financial Group Inc. as more troubled, even as Assured's own risks mount. Fitch Ratings, in stripping its AAA insurance grade three days ago, cited Assured's backing of both home-loan debt and $7.3 billion of securities tied to preferred notes from banks, insurers and real-estate investment trusts.

It is "easy to assume losses could be substantial even at the highest level of the deal structure", Andrew Wessel, an analyst at JPMorgan Chase & Co, wrote in a May 5 report, referring to the so-called trust preferred securities collateralised debt obligations linked to companies suffering from a collapse in property prices. "We believe this uncertainty will continue to weigh on" Assured's shares.

While chief executive officer Dominic Frederico has benefited from his resistance to CDOs of subprime-mortgage bonds, other guarantees tied to home loans and different CDOs are buffeting the market-share gains that he plans to build on by buying rival Financial Security Assurance Inc.