Dow Jones Industrial Average index slipped on Monday as the drop in Chicago PMI boosted worries the overall manufacturing gauge on Tuesday also may show slow down. Blue chip index gave up 0.11% or 14.68 points and closed at 13,213.63. Merck & Co posted the biggest gains for the Dow as court ruled company's patent cholesterol drugs Zetia and Vytorin is valid. On the downside banks declined following raising tensions among their European counterparts. Bank of America fell 1.7% and JP Morgan shed 0.8%.