July 23 (Reuters) - Wall Street's main indexes opened lower on Thursday, as concerns over heavy AI spending resurfaced after the first batch of Big Tech earnings, while another jump in oil prices linked to the widening Middle East conflict further dampened sentiment.

The Dow Jones Industrial Average .DJI fell 463.0 points, or 0.89%, at the open to 51755.54. The S&P 500 .SPX fell 80.7 points, or 1.08%, at the open to 7418.29​, while the Nasdaq Composite .IXIC dropped 445.4 points, or 1.73%, to 25245.542 at the opening bell.