(Updated for closing prices)NEW YORK ( TheStreet) -- Shares of the U.S. health insurers got off to a quick start on Wednesday when news of the demise of the public option in the congressional healthcare overhaul and comments made by Aetna's ( AET) CEO buoyed the sector. However, those quick gains were muted by the end of Wednesday, as still new concerns about revenue spending requirements surfaced. Thursday was a different story, though, as the gains in the sector from early in the trading day remained at the market close, with some HMOs, like Health Net ( HNT), achieving 52-week high levels. Health Net closed up 4.5% on Thursday to $23.76, 3 cents below the 52-week high it reached earlier in the trading session. The biggest gainers overall on Thursday were UnitedHealth Group ( UNH), which was up 6.4%; Cigna ( CI), up 6.1%; WellCare Health Plans ( WCG), up 5.5%; and Aetna, up 5.2%. Coventry Health Care ( CVH) was up 4%; while Humana ( HUM) was up 2.8%. WellPoint ( WLP), the laggard of the group, was up 1.8% at mid-day. -- Reported by Eric Rosenbaum in New York. >>See our new stock quote page. Follow TheStreet.com on Twitter and become a fan on Facebook.