NEW YORK (AP) — The New York Stock Exchange says an outage of more than three hours was caused by problems associated with a software upgrade on the exchange's computers.

The NYSE said in a statement Thursday that the upgrade caused communication problems between its trading software and other systems, causing customers' orders to not go through.

The problem became severe enough by late morning Wednesday that the exchange decided to suspend trading at 11:32 a.m. Eastern time so the problem could be addressed. The exchange restarted trading at 3:10 p.m. Eastern.

Wednesday's shutdown was a black eye for the NYSE, but ultimately it did not broadly impact Wednesday's trading. The Nasdaq still operated normally and several other exchanges were available for investors to execute trades while the NYSE worked through its problems.