U.S. stock market trading suspensions

Major U.S. stock exchanges have closed in the wake of major storms and blackouts and to mark wars and the deaths of presidents and monarchs (Queen Victoria in 1901). But in the computer age, technical glitches also have forced trading to halt.

1987: A squirrel on a power line cut the power to a Nasdaq Stock Market computer center in Connecticut, forcing the exchange to close for about 80 minutes on Dec. 9.

1994: Another squirrel triggered a dip in power, forcing the Nasdaq to close for more than 30 minutes on Aug. 2.

2001: U.S. stock markets close for a week after the Sept. 11 terrorist attacks.

2013: A server malfunction forced a three-hour trading halt on the Nasdaq on Aug. 22.

Yesterday: An unspecified "technical issue" prompted a 31/2-hour halt in trading on the New York Stock Exchange.