Stocks dip as Nancy Pelosi's Asia trip rattles investors

Wall Street opened lower Tuesday as a possible visit by U.S. House Speaker Nancy Pelosi to Taiwan has prompted threats from Beijing of a military response. 

The S&P 500 declined 24 points to 4,095, or 0.6% in morning trading. The Dow Jones industrials fell 0.8% and the Nasdaq slid 0.5%.

"Tensions between U.S, and China are likely to intensify given Pelosi's intended visit to Taiwan, and the risks of an accident are likely underappreciated by markets," TD Securities analysts said in a client note.