NEWYORK(Reuters)-U.S.stockandoptionsmarketswillbeclosedonMonday,andpossiblyTuesday,asregulators,exchangesandbrokersworryabouttheintegrityofmarketsandthesafetyofemployeesinthefaceofHurricaneSandy.MarketparticipantsandregulatorsdecidedlateonSundaytoshutthemarket,reversingaplantokeepelectronictradinggoingonMonday.Bondmarketswillremainopen,butwillcloseatnoon,atradegroupsaid.Thedecis...