Rio Tinto RIO.AX, BHP Group BHP.AX and Fortescue Metals Group FMG.AX fell between 1.1% and 2.3%. By Archishma Iyer Oct 17 (Reuters) - Australian shares slumped on Monday, with commodity companies leading broad declines as searing inflationary pressures and worries about a potential global recession weighed on investor confidence. Wall Street dropped on Friday as worsening inflation expectations kept intact worries that the Federal Reserve's aggressive rate hike path could trigger a recession.