A day after the biggest loss of the year for the Dow Jones Industrials (DJINDICES:^DJI), investors took the opportunity to look on the bright side of things. With favorable economic data on the housing front and assurances from Fed Chairman Ben Bernanke that the central bank isn't going to abandon its efforts to get the economy back on an even keel, the stock market managed to post a fairly strong rebound, gaining back more than half its Monday losses to climb 116 points. Broader market measures were up somewhat less, rising by about half a percent.

Yet among the losing stocks, Dow component UnitedHealth (NYSE:UNH) fell 0.5%. Health insurers did especially badly last week, with UnitedHealth dropping 5% on the prospect that the Centers for Medicare and Medicaid Services could slash reimbursement rates next year for Medicare Advantage supplemental insurance policies, and with the debate over sequestration starting to heat up, similar arguments are likely to go on for the foreseeable future. Still, smaller players with greater concentrations to Medicare Advantage could get hit even more, arguably putting UnitedHealth in a more favorable position with its more diversified portfolio of insurance offerings.

Elsewhere, VIVUS (NASDAQ:VVUS) fell 12% after reporting a slow quarter of sales for its weight-loss drug Qsymia. With Europe's drug regulatory agency recommending further safety tests for Qsymia last week but also requesting additional information for Arena Pharmaceuticals (NASDAQ:ARNA) rival anti-obesity drug Belviq, it's unclear whether either company will make progress in its fight to gain a lasting advantage in the weight-loss market. Arena fell 3% on the day.

Finally, First Solar (NASDAQ:FSLR) dropped 4% in advance of its afternoon earnings release, in which it reported record fourth-quarter sales. But revenue guidance for the current quarter of $650 million to $750 million came in well below analyst projections of more than $825 million, and shares initially reacted negatively to the news with further losses in after-hours trading right after the announcement. With the solar industry having bounced back sharply in recent months, First Solar will need to work even harder to produce the growth necessary to keep investors satisfied.

Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter @DanCaplinger. The Motley Fool recommends UnitedHealth Group. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.