UPDATE 1-Freddie's Bitsberger follows Syron, Cook departures

NEW YORK, Nov 18 (Reuters) - Freddie Mac, the second-biggest provider of funding for U.S. residential mortgages, said on Tuesday Treasurer Timothy Bitsberger will be at least the third executive to leave the company this month.

Bitsberger joined Freddie Mac (FRE.P) in November 2005 after working as assistant secretary for financial markets at the U.S. Treasury. He will be replaced by Peter Federico, a senior vice president of asset and liability management.

His departure follows that of Richard Syron as chief executive officer of the McLean, Virginia-based company this month. Freddie Mac's chief business officer, Patricia Cook, has left as of Nov. 17, according to a regulatory filing.

A Freddie Mac spokeswoman confirmed the departure of Bitsberger and "some" lower level employees. The Wall Street Journal reported Bitsberger's exit earlier on Tuesday.

Freddie Mac and rival Fannie Mae have struggled during the two-year housing downturn, losing billions as foreclosures increase its credit costs. Concerned about their ability to purchase mortgages and stabilize housing, the government forced the companies into conservatorship in September.

Borrowing costs for the companies have soared in part due to uncertainty over the level of government's support of their $1.6 trillion in debt outside of conservatorship. The companies have been directed to pare investments by more than two-thirds after 2009, stripping them of reliable revenue streams.

The Treasurer is responsible for debt issuance, which has been hindered by the rising costs and slackened demand.

Freddie Mac last week said uncertainties over future regulation and its business model may be putting it at a competitive disadvantage. The inability to retain or replace employees with key skills could adversely affect the business and slow a return to profitability, it said. (Reporting by Al Yoon; Editing by Tom Hals)