Radian Group Inc., the Philadelphia-based mortgage insurer, says it has agreed to sell its New York-based financial-guaranty insurance unit, Radian Asset Assurance Inc, to a unit of Assured Guaranty Ltd., for $810 million. The business, with risk exposure totalling $19.4 billion, employs about 35 (revised). Buyer Assured, based in Bermuda, is led by Dominic Frederico, a Drexel graduate who was formerly a top executive at Ace Ltd.

Shares of Radian rose above $17 in early trading today. The stock tends to rise and fall with the U.S. housing market and the opportunities and risks in home finance: Shares topped $60 in 2006-7, and plunged to $2 as recently as 2012 after losses from insuring mortgage-backed derivative securities. Radian Asset hasn't written new business since 2008, says Radian spokeswoman Emily Riley. Radian's workforce had roughly doubled this year, to 1,730, since the company's acquisitions of Clayton Holdings and Green River Capital; about 530 work in Philadelphia.

"We look forward to simplifying Radian's focus on our core strengths, which we believe will pave the way for future top-line growth," Radian chief executive S.A. Ibrahim (a Wharton grad) said in a statement. Ibrahim tied the sale to the Federal Housing Agency's proposed tighter new Private Mortgage Insurer Elegibility Requirements (PMIERs), which would oblige insurers like Radian Asset to restrict the application of capital used to insure mortgage bonds from inclusion in the company's own capital ratios. (Revised)