Symetra Financial Corp. plans to make an initial public offering of common stock.

Symetra, Bellevue, Wash., says the IPO will include some stock that it owns and some held by existing stockholders. The stock to be sold will have a total value of about $575 million.

Symetra hopes to list its shares on the New York Stock Exchange under the symbol “SYA.”

The company is now owned by an investment group led by White Mountains Insurance Group Ltd., White River Junction, Vt., and Berkshire Hathaway Inc., Omaha, Neb. After the offering is completed, White Mountains and Berkshire Hathaway will “continue to beneficially own common stock in the company,” Symetra says.

Symetra was formed in 2004, when Safeco Corp., Seattle, divested itself of its life and annuity operations.

Symetra generated about $22 million in net income in 2008 on $1.5 billion in revenue by selling products such as medical stop-loss insurance, limited medical benefit plans, group life insurance, accidental death and dismemberment insurance and group disability insurance.

Symetra also sells individual life insurance; immediate annuites; fixed and variable deferred annuities; and group annuities designed for use in retirement plans.

The company distributes products nationally through about 3,500 benefits brokers, 15,000 independent agents, and 26 large financial institutions.

Symetra intends to use the proceeds from the stock offering for “general corporate purposes,” which could include contributions of capital to life subsidiaries, and also could include “pursuit of its growth strategies,” the company says.