US stock index futures were mostly flat, continuing their strong run on Monday as markets bet the Federal Reserve would soon signal it was ready to start cutting interest rates. Traders took a breather after the S & P 500 strengthened for an eighth straight day on Monday. Stock volumes fell and investors were reluctant to make big bets ahead of this week's Jackson Hole economic conference. Kyle Rodda, senior market analyst at Capital.Com Inc., said: "What we have seen is that the recent series of data has eased concerns about a slowdown in U.S. growth without raising concerns about a reacceleration in inflation."