The New York Stock Exchange has received a credible threat to its external website, prompting the Big Board to beef up its security and monitoring for a potential cyber attack, FOX Business has learned.

The NYSE declined to comment specifically on the threat.

“We don’t comment on security matters. However, we take security-related issues very seriously,” said NYSE spokesman Richard Adamonis.

However, a source familiar with the matter told FOX Business the iconic Big Board is “on alert for an attack” and has received “credible threats.”

The NYSE typically goes on alert “when there is a reasonable assumption of a large imminent threat or capable threat,” the source said.

The threats on Thursday center around a potential denial-of-service attack that is strictly focused on the exchange’s external website and has nothing to with its trading systems, a separate source said.

It’s unclear whether an attack has occurred or just that NYSE received information that one could come on Thursday. There are no obvious signs of disruptions to trading or the NYSE’s website.

The source of the threat is unknown, but the Big Board has been the target of anti-capitalist cyber groups like Anonymous in the past.

Earlier this year, pro-Palestinian hackers disrupted the websites of the Tel Aviv Stock Exchange as well as the Israeli central bank and other financial institutions.

Last year the Nasdaq OMX Group disclosed an infiltration into a confidential document-sharing service it controls.

(Source: Newscore)