The S&P 500 rose 1.79% to close at 7,736.52, after opening at 7,630.62. The Aug. 5 Polymarket contract implied an 87% probability that the index will open higher on Wednesday. Why That Number MattersTuesday's rally pushed the S&P 500 above the 7,700 level for the first time ever, with both the benchmark index and the Dow Jones Industrial Average notching fresh record closes. S&P 500 futures added 0.39% early Wednesday. The S&P 500 opened at 7,630.62, above Monday's close of 7,600.50, meaning the contract ultimately resolved "Up."