Former New York City Mayor Michael Bloomberg announced Wednesday that he will reassume control over Bloomberg LP, the financial data and news company he founded in 1981, when current CEO Daniel L. Doctoroff steps aside at the end of this year. “This is a sad day for me and my company,” Bloomberg said, referring to Doctoroff's departure.

Doctoroff, who joined Bloomberg LP as president in 2008 and became CEO in 2010, first collaborated with Bloomberg as deputy mayor for Economic Development and Rebuilding for New York City. Under his tenure, company revenues increased from $5.4 billion to $9 billion, while the number of subscribers to Bloomberg LP’s lucrative data terminals business increased from 273,000 to 321,000.

Bloomberg was effusive in his praise of Doctoroff.

“Under Dan’s leadership, our position in every market in which we compete is the strongest it has ever been,” the former mayor said.

“I’ve said it many times before, Dan’s record in City Hall and at Bloomberg demonstrates he is one of the finest leaders and managers I have ever known.”

But while Doctoroff noted that he “loved” the company and that “leaving was not an easy decision,” the New York Times’ Andrew Ross Sorkin reported that the outgoing CEO had grown frustrated at Bloomberg’s increased role in the company. At the conclusion of his third mayoral term in January, Bloomberg announced that he would devote much of his time to philanthropic causes. In recent months, however, the former mayor became a much more regular presence at his old firm.

“It isn’t the job I had for the past six years,” Doctoroff told Sorkin. “It’s his -- he wants to be involved. He doesn’t want to consult with me on everything. I get that.”