Deputy Mayor Daniel Doctoroff, the architect of the city’s economic development agenda for the past six years, is leaving his post at City Hall to become president of Bloomberg LP.

Beginning next year, he will hold the no. 2 position at the financial services company founded by Mayor Bloomberg. The chairman of the company, Peter Grauer, will give up the title of president.

Mr. Doctoroff, who will oversee almost 10,000 employees, said yesterday he is pleased to be joining a leading global organization in an industry he is passionate about, and that he is thrilled “to remain part of the Bloomberg family.”

Mr. Bloomberg told reporters that Mr. Doctoroff’s departure was bittersweet, and added that he hoped to find someone even better to take over as the city’s economic development chief.

“I’ve met many extraordinary people with first-rate intelligence and inspiring passion and exceptional creativity, razor sharp financial acumen, a tireless work ethic, and tremendous ability to turn bold visions into reality,” Mr. Bloomberg said. “But I don’t know if I’ve met anyone who combines these gifts as well as Dan Doctoroff.”

Mr. Doctoroff, who led the city’s failed bid to host the Olympics, said he hoped to stay involved in some capacity in city projects, including the development of Hudson Yards on the far west side of Manhattan and Mr. Bloomberg’s environmental proposal, PlaNYC.

Mr. Bloomberg said his administration has had virtually no turnover since he was elected, but added that it’s normal for his staff members to think their next steps.

The mayor said that he recently considered selling the company but decided against it, adding that Bloomberg LP is not for sale, is not going to change management, and is not looking to acquire new businesses.

Like Mr. Bloomberg, Mr. Doctoroff is paid an annual salary of $1. He ran a private equity firm before becoming deputy mayor, and joked that he sometimes would be asked if he regretted missing out on the biggest boom in private equity.

“I would have done this job for nothing,” he said, prompting laughter because he basically did. Mr. Doctoroff said he has no desire to re-enter public life.

The chairman of the mayor’s Committee on Appointments, Nathan Leventhal, is beginning talks with a small group of possible candidates to replace Mr. Doctoroff. The commissioner of the department of Housing, Preservation, and Development, Shaun Donovan, is considered a potential replacement to Mr. Doctoroff.