Symetra Financial Corp., a Bellevue, Wash.-based life insurance company, has filed for a $750 million IPO. It plans to trade on the NYSE under ticker symbol SYA, with underwriters including Merrill Lynch, Goldman Sachs, JPMorgan and Lehman Brothers. Shareholders include Vestar Capital Partners, Och-Ziff Capital Management, Highfields Capital Management, Caxton Associates, White Mountains Insurance Group and Berkshire Hathaway. www.symetra.com