Intelligence officials stress the threats are general in nature and there is "no indication of a targeted assassination plot" against any Wall Street executive. But NBCNewYork.com has learned officials fear the names of some top banking executives have been discussed by terror operatives overseas.
Intelligence analysts added they have a general but growing concern that operatives in Yemen may again try to send package bombs or biological or chemical agents through the mail to Wall Street bankers.
In recent weeks, the FBI's Joint Terrorism Task Force and NYPD officials have been briefing bank executives and their security departments on the nature of the threat information. Much of it gleaned from al Qaeda writings like 'Inspire' magazine that recently warned of attacks targeting financial institutions.
The latest "Inspire" issue also made reference to trying to use Anthrax in an attack, officials said.
NBC terror consultants also point to the web writings of al Qaeda blogger Abu Suleiman Al-Nasser, who recently wrote,"Rush my Muslim brothers to targeting financial sites and the program sites of financial institutions, stock markets and money markets."
Al-Nasser is a blogger who has written about some previous al Qaeda plots -- including a recent bombing attempt in Sweden -- before much of the information was publicly known.
Banks like Goldman Sachs, Citibank, JP Morgan Chase, Barclays and others have received updated security briefings from the FBI's JTTF, security officials told NBCNewYork.
Spokesmen for numerous banks declined to comment, instead referring all calls to law enforcement agencies.
Spokesmen for the NYPD, FBI and homeland security offices also declined comment about the recent briefings.
Wall Street banks do get regular security updates but one official familiar with the latest briefings said there was added concern even though the threat information is non-specific.
As a precaution, police are urging Wall Street banks to further increase security in and around mail rooms and delivery of packages - especially those that might be addressed to those firms' top executives.
Part of this warning also comes as the result of last October's failed plot by Yemen terrorists to exploded package bombs on airliners bound for U.S. cities.
Since 9-11, the NYPD has greatly stepped up security around Wall Street. Terror suspects have been caught scouting targets like the Citicorp Center and the New York Stock Exchange.
Congressman Peter King (R-Long Island), who himself has extra security after his name appeared in a recent issue of "Inspire," said when al Qaeda terrorists publish threats, those threats should be taken seriously.
"Whenever a name is included ... it's always a cause for more concern, because again the fear is that that's sending a specific signal to specific operatives in this country to take action," said King, chair of the House Homeland Security Committee.
Security officials said any banking executive whose name may have been discussed by al Qaeda-linked operatives overseas has been notified.