Essent Group Ltd., the mortgage insurer backed by George Soros and Goldman Sachs Group Inc., is seeking a valuation of $1.2 billion in an initial public offering as the company adds capital to expand sales.

Essent and its investors are selling 19.7 million shares for $13.50 to $15.50 apiece, according to a regulatory filing today from the Bermuda-based firm. At the midpoint, that would raise about $286 million for a 24 percent stake.

Investors have poured capital into mortgage insurers this year amid rising home prices. Essent was started during the housing bust as homeowners’ defaults drained capital from firms that backed mortgages issued before the crash.

“The new capital would help fund Essent’s continued growth, lower its operating leverage, increase its cash on hand and demonstrate its ability to raise capital,” Helen Remeza, an analyst at Moody’s Investors Service, said in a note before the offering. “A capital raise could also further differentiate Essent Guaranty from its more weakly capitalized peers.”

Goldman Sachs, JPMorgan Chase & Co. and Barclays Plc are leading the offering. Essent has sold most of its coverage in the past two years, and had a 12 percent share of the traditional market in the first six months of 2013.

Essent’s net income was $46.4 million in the first nine months of 2013, compared with a loss of $14.6 million in the same period of 2012, according to today’s filing. The company sold coverage on $16.6 billion of loans in the first three quarters of 2013, up from $7.2 billion.

JPMorgan, Valorina

Goldman Sachs is selling 1.5 million of its shares in the offering, reducing its stake to about 7 percent, according to today’s filing. JPMorgan is selling 1.2 million. Essent plans to sell 17 million shares.

Soros’s Valorina doesn’t plan to sell shares, and its stake will be about 9 percent after the offering.

Radian Group Inc. and MGIC Investment Corp. are the main companies that focus on U.S. mortgage insurance. Their shares have more than doubled this year, and both firms raised capital in early 2013 to make up for crisis-era losses. American International Group Inc. and Genworth Financial Inc. also offer mortgage coverage.

In the twelve months through July, home prices in 20 U.S. cities increased 12.4 percent, the biggest jump in seven years, according to the S&P/Case-Shiller index.

Mortgage insurance is typically required when borrowers pay less than 20 percent of the cost of their home up front. Private firms provided a majority of the coverage before the crisis, while U.S. government entities led by the Federal Housing Administration sold more amid the crash.

Essent was founded by Mark Casale, a 49-year-old former Radian executive. The company said in May 2009 it had received a commitment of $500 million from investors including JPMorgan, Goldman Sachs and Pine Brook Road Partners LLC. The backers agreed in 2010 to make another $100 million investment.

Editors: Dan Reichl, Julie Alnwick