SAN FRANCISCO (KRON) — It came as a shock to a lot of people Wednesday when the New York Stock Exchange shut down for nearly four hours.

The problem was supposedly some kind of internal malfunction.

There was no interruption at the dozens of other U.S. stock exchanges Wednesday, including the Nasdaq, so investors were still able to buy and sell stocks easily. The market was already lower as traders worried about China’s failure to halt a plunge in its shares and talks remained stuck between Greece and its lenders.

Our financial expert Rob Black joins Catherine Heenan to talk about what happened.