Haines, founding anchor of CNBC's morning show "Squawk Box," was co-anchor of the network's "Squawk on the Street" program, providing insight and commentary sometimes humorous and occasionally acerbic.

CNBC President Mark Hoffman called Haines a "building block" of the financial network's programming. Hoffman said Haines died at his home.

"With his searing wit, profound insight and piercing interview style, he was a constant and trusted presence in business news for more than 20 years," Hoffman said in a statement to CNBC employees. "From the dotcom bubble to the tragic events of 9/11 to the depths of the financial crisis, Mark was always the unflappable pro.

"Mark loved CNBC and we loved him back. He will be deeply missed."

Haines may be best remembered for his calming and commanding presence during the 9/11 tragedy when he reacted unflappably to the furious stream of incoming rumor and even more astonishing truth with a professionalism that rivaled any television anchor, said CNBC senior economics reporter Steve Liesman.