Boston-based investment bank State Street Corp. has entered into an agreement to acquire Pulse Trading Inc., a national agency brokerage firm.

The deal is expected to close in the fourth quarter of 2011, pending regulatory and other closing conditions.

Pulse Trading is a full-service agency brokerage firm headquartered in Boston with a range of electronic trading capabilities that include block crossing and blotter scraping technology. The transaction includes the acquisition of Pulse Trading’s institutional equities business and approximately 40 employees in Boston, New York, St. Louis and San Francisco.

"We look forward to joining State Street where we will continue bringing best-in-class trading technology to our institutional clients," said Christian Dubois, managing partner at Pulse Trading. "The combination of our products with State Street’s scale and institutional client base will allow us to expand our reach."

"The acquisition of Pulse Trading is a natural extension of State Street Global Markets’ neutral, agency model," said David Puth, executive vice president of State Street Global Markets. "Pulse Trading’s sophisticated technology and block trading capabilities will expand the number of execution venues and the range of electronic trading tools available to our clients and ultimately help lower their trading costs."