The stock market will not necessarily close due to a power outage provided that markets can be kept open by backup generators or by some other means. However, there have been many instances of the stock market closing due to power outages, software errors, telecommunications cable failures, terrorist attacks and even solar radiation.
In 2012, U.S. stock exchanges were forced to close due to weather conditions caused by hurricane Sandy. During the storm, markets were able to stay open for a limited time by running on emergency generators. The New York Stock Exchange was closed for two consecutive days due to weather conditions, power outages and connectivity issues. This was the longest weather-related shutdown since 1888.
In 1987 and 1994, the Nasdaq stock market was shut down temporarily due to squirrels causing power line failures and subsequent power outages. The shutdowns only lasted a few hours until power could be restored. Although these shutdowns were not anticipated and caused some anxiety, trading resumed after power was restored.
From Sept. 11-14 in 2001, the New York Stock Exchange was closed due to terrorists' destruction of the World Trade Center. The exchange also has halted trading intermittently over the years due to computer glitches, or for moments of silence to mourn victims. In October of 1997, the New York Stock Exchange closed early due to massive drops in the Dow Jones industrial average. Steep declines trigger computerized trading halts to avoid wide index swings and instability.
Foreign stock exchanges also have been forced to close for various reasons. In 2005, the Tokyo Stock Exchange was forced to close due to a software bug that forced main servers and backup servers to crash. Trading was suspended for four and a half hours. In 2005, a power outage in Moscow caused markets to close for more than two hours. Although the Moscow Interbank Currency Exchange itself was unaffected by power outages, the outages caused many of the exchange's clients to go without power, eliciting the need for the closure.
- Allianz: Power Blackout Risks
- Allianz: Energy Risks -- the Dangers of Power Cuts and Blackouts
- Forbes: Stock Exchanges Shift To Contingency Plans As Sandy Wreaks Havoc
- Financial and Banking Information Infrastructure Committee: Impact of the Recent Power Blackout and Hurricane Isabel on the Financial Services Sector
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