July 20 (Reuters) - Wall Street"s main indexes opened higher on Tuesday, as economically sensitive stocks rebounded following a sharp selloff in the previous session, while shares of IBM jumped on strong second-quarter results. The Dow Jones Industrial Average (.DJI) rose 19.8 points, or 0.06%, at the open to 33981.79. The S&P 500 (.SPX) rose 6.6 points, or 0.16%, at the open to 4265.11​, while the Nasdaq Composite (.IXIC) rose 55.5 points, or 0.39%, to 14330.462 at the opening bell.