NEW YORK – Wall Street closed a volatile week on a muted note on Sept 18 as benchmark US Treasury yields topped 5 per cent, while crude prices reversed earlier gains but remained above US$100 (S$127) per barrel, keeping inflation worries front and centre.The session capped a week that was essentially split in two: first, restless anticipation in the days before the US Federal Reserve’s widely expected interest rate hike, followed by the aftermath of that decision.A semiconductor rally boosted the Nasdaq and the S&P 500, but broader weakness pulled the Dow to a lower close.The S&P 500 ended the…