A jury said the drug maker gave doctors adequate warnings about the possible health risks from its painkiller, Vioxx.
Shares of Merck climbed 6.8 percent to $30.35 on the New York Stock Exchange.
The Dow Jones industrial average was up 72.76 points, or 0.69 percent, at 10,545.49. The Standard & Poor's 500 Index was up 7.41 points, or 0.61 percent, at 1,222.17. The technology-laced Nasdaq Composite Index was up 18.58 points, or 0.87 percent, at 2,162.89.