CNBC’s Mark Haines died unexpectedly Tuesday night at age 65. Haines was the founding anchor of the network’s popular Squawk Box program and co-anchor of Squawk on the Street with Erin Burnett, who recently left CNBC for CNN. From CNBC’s report on Haines’ death:

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.

Known as both an aggressive and comical on-air personality, Haines got into his fair share of scuffles with guests over the years. Here he is ruffling Barney Frank’s feathers.