Gilead Pharmaceuticals (GILD) plunged over 14% on Monday, making it TheStreet's Move of the Day. The pharmaceutical giant learned its expensive Hepatitis-C drug, which costs $84,000 would no longer be covered by the nation's biggest drug benefits manager, Express Scripts. Gilead's competitor AbbVie saw its Hepatitis-C drug approved by the FDA last Friday and costs about $700 less than Gilead's. But AbbVie was able to strike an even better deal at a much lower undisclosed price with Express Scripts. Shares of Gilead ended the trading day closing at $92.90 per share. The stock is up 23.7% year-to-date. AbbVie's stock closed down just over 1% to 66.97 per share. TheStreet's Scott Gamm has details from New York.