Wall Street closed mostly flat on Wednesday trading session with the benchmark index Standard & Poor's swinging between gains and losses after companies from Verizon to Johnson & Johnson reported disappointing earnings. The Dow Jones industrial average slipped 0.25% to 16,373.34, the S&P 500 Index added 0.06% to 1,844.86 and the Nasdaq Composite Index gained 0.41% to 4,243.