Nashville-based hospital chain HCA Inc. is working toward a new public stock offering that could raise at least $3 billion and attract new investors to the broader hospital industry, The Tennessean reports. If successful it would mark HCA's return to being publicly traded after going private three and a half years ago in a sale to private equity firms KKR & Co., Bain Capital LLC, Bank of America, and members of Nashville's Frist family. A public stock offering also would be a vehicle through which HCA's owners could cash in some of their ownership stakes and raise money to pay off some of the hospital company's debt, according to The Tennessean.