Medtech companies including Dexcom DXCM.O, Insulet PODD.O and Abbott ABT.N rose as analysts discussed data about the cardiovascular benefits for Novo Nordisk's NOVOb.CO weight-loss drug Wegovy. By Sinéad Carew and Sruthi Shankar Nov 13 (Reuters) - The S&P 500 closed Monday's session slightly down as investors held their breath before a crucial inflation reading that could provide clues as to how long the U.S. Federal Reserve will keep interest rates elevated. Moody's late on Friday lowered its outlook on the U.S. credit rating to "negative" from "stable", citing large fiscal deficits and a decline in debt affordability.