Michael Bloomberg Returns To Head Bloomberg L.P.

FILE - In this Dec. 18, 2013, file photo, Mayor Michael Bloomberg speaks in New York. The former New York mayor was the No. 4
FILE - In this Dec. 18, 2013, file photo, Mayor Michael Bloomberg speaks in New York. The former New York mayor was the No. 4 philanthropist in 2013, The Chronicle of Philanthropy reported, Monday, Feb. 10, 2014. Bloomberg made gifts totaling $452 million in 2013 to arts, education, environment, public health and other causes. (AP Photo/Bebeto Matthews, File)

Former New York City Mayor Michael Bloomberg is heading back to take the reins of the company he founded, just eight months after leaving the mayor's office.

A statement from Bloomberg L.P. said that Daniel L. Doctoroff would be stepping down as President and CEO, effective at the end of the year, and Bloomberg would replace him.

The New York Times, which first reported the story, said Bloomberg had been spending more time at the company in recent months, but the return to a larger role was unplanned. Bloomberg, who owns 88 percent of the company, told the Times, "This wasn’t the plan," and, "It was his idea," referring to Doctoroff who joined the former mayor Wednesday afternoon. "If it was up to me, he would have stayed," Bloomberg said.

Doctoroff reportedly announced he would be leaving two weeks ago, citing tension arising over Bloomberg's increasing presence at the company. "When Mike decided he wanted to spend some time at the company, and then spent more time, obviously things changed,” Doctoroff told the Times, adding, "It isn’t the job I had for the past six years. It’s his -- he wants to be involved. He doesn’t want to consult with me on everything. I get that." Bloomberg urged him to remain in his position, but his efforts were unsuccessful. Doctoroff is to take a position on the board of his foundation.

In the company statement, Bloomberg said of Doctoroff, "Dan will always be a part of the Bloomberg family -- he will continue to be my friend, advisor and partner for years to come. I have asked him to join the Board of Bloomberg Philanthropies and I’m sure I will personally support future initiatives he decides to pursue." The Times notes that Bloomberg and Doctoroff's long-time friendship remains intact, despite the disagreement over company leadership.

Doctoroff joined the company in 2008, following his role as Bloomberg's deputy mayor, working in private equity, and as an investment banker at Lehman Brothers.

Bloomberg, who founded the financial data and media company in 1981, said he felt energized in his return to the company, and that he would continue his work for philanthropic efforts, such as gun control, immigration and public health.

This is a developing story. Check back for updates.