Shares of drugmaker Merck & Co. slipped in extremely heavy trading Monday, three days after a Texas jury hit the company with a $253.4 million damage award in the first trial over withdrawn painkiller Vioxx.

While the award likely will be slashed on appeal, the news unsettled investors, cutting the stock’s price 3 percent in the first minute of trading. But Merck shares recovered to $27.89 late Monday, down 17 cents.