Q. On July 8, 2015, trading on the New York Stock Exchange (NYSE) was temporarily halted for a few hours as the result of “an internal technical issue” that was “not the result of a cyber breach.” Does that affect PortfolioCenter? A. PortfolioCenter only needs to know if all US markets are closed for the entire day — as when Hurricane Sandy closed the markets for two days in 2012.
The large NYSE is not the only stock exchange. Trades were simply rerouted to other exchanges (NASDAQ or NYSE ARCA), both of which normally have higher trading volumes.
For the most accurate Time-Weighted Rate of Return (TWR) and Internal Rate of Return (IRR) calculations, PortfolioCenter needs to know the dates the markets are closed. Normal US tock market holidays are built in to the program.
Only unexpected closures require intervention.
While small technical glitches have resulted in major outages — including Google blocking the entire internet with a data entry mistake, NASA crashing a Mars Orbiter because they failed to convert to the metric system, and the Navy leaving the USS Yorktown dead in the water when they divided by zero, — as long as some US markets are open at least part of the day, PortfolioCenter is not affected.
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