Stocks extended losses in the final hour, after oil logged its worst daily drop since February 11. Crude fell below $40 a barrel after domestic inventories came in far higher than estimates in the past week. Virgin America (VA) spiked on reports it is considering a sale. The airline is allegedly reaching out to potential buyers, a number of which have expressed interest. Yum! Brands (YUM) - Get Report jumped on reports it is contemplating unloading a stake in its Chinese operation. The KFC owner could sell a stake as large as 20% for around $10 billion. Merck (MRK) - Get Report climbed after a federal jury in California ruled in its favor in a lawsuit against rival Gilead Sciences (GILD) - Get Report . Merck accused Gilead of infringing upon several key hepatitis C patents. The drugmaker is seeking billions in damages and royalties. TheStreet's Keris Lahiff reports from Wall Street.