Headlands Mortgage Co., a specialty banking company that focuses on mortgages for one- to four-family residences, plans to sell 8 million common shares in an initial public offering, raising as much as $62 million after expenses. The mortgage company, based in Larkspur, filed with the Securities and Exchange Commission for the first-time stock sale, saying new investors would own 24.3% of the 18.5 million shares outstanding after the offering. Headlands plans to sell 4.5 million shares in the offering at $14 to $16 each. Based on a median price of $15 a share, and the shares that would be outstanding, the offering implies Headlands has a market value of $277.5 million. Headlands specializes in mortgages for "high-credit quality borrowers," the filing said. Company founder Peter T. Paul would sell 3.5 million shares in the offering and retain a 56.8% stake after the sale.