Stocks fell the most in more than two weeks Wednesday and erased the bulk of the week’s gains. The Nasdaq and S&P 500 fell 0.7% each, while the Dow Jones industrial slumped 1%. Preliminary numbers showed that volume, which had been tracking lower, finished mixed, up on the NYSE and down slightly on the Nasdaq exchange. Leading stocks felt the brunt of the damage in the stock market today as 47 of the IBD 50 stocks took a tumble.