If a U.S. recession becomes more likely, Goldman Sachs GS.N said investors should maintain upside exposure to equities by using options to hedge a potential 23% fall in the S&P 500 index .SPX. Fellow postal operator United Parcel Service UPS.N slipped 1.2%. By Shubham Batra and Johann M Cherian June 21 (Reuters) - Wall Street's main indexes fell on Wednesday as Federal Reserve Chair Jerome Powell remained firm in bringing inflation back to 2% target, spurring worries of more monetary tightening.