Wall Street's main stock indexes opened lower on Thursday as simmering Middle East tensions lifted oil prices and Treasury yields, while investors also exercised caution ahead of a keenly watched summit between Presidents Donald Trump and Xi Jinping.The Dow Jones Industrial Average fell 95.8 points, or 0.19%, at the open to 51415.75. The S&P 500 fell 39.0 points, or 0.51%, at the open to 7666.99?, while the Nasdaq Composite dropped 201.5 points, or 0.75%, to 26734.508 at the opening bell.More to come…