Walter Investment Management Corp. (WAC) on Friday said its Green Tree unit will begin servicing about 4,000 Bank of America Corp. (BAC) mortgages this month as part of the bank's mandate to hire delinquent-loan specialists under a widely watched investor settlement.

Green Tree in October was one of nine troubled debt experts named to tackle the estimated 300,000 mortgages identified under the $8.5 billion faulty-loan settlement between Bank of America and big mortgage investors including BlackRock Inc. (BLK) and Pacific Investment Management Co.

The arrangement with so-called "special servicers" is moving ahead despite legal challenges to the monetary settlement. Green Tree is the fourth special servicer to receive an installment of loans under the settlement, according to a person familiar with the transactions.

Bondholders expect that loans in their securities will be treated by specialists sooner, avoiding delays that often result in higher costs and lower returns on the bonds. Having Bank of America give up some responsibility for the most delinquent loans was a key part of the settlement for the investors, who have trouble obtaining information and enforcing trustees to act when they see their bonds mishandled by primary servicers.

For Walter, the business helps replace servicing lost as other loans mature or are retired in foreclosure. The Bank of America loans and another expected "delinquency flow" program later this year will provide enough business to offset the monthly runoff by year end, Walter Chief Executive Officer Mark O'Brien said in a statement.

Walter expects a significant increase mortgages serviced under the settlement as it was approved to receive up to 30,000 units.

A Bank of America spokeswoman declined immediate comment.

-By Al Yoon, Dow Jones Newswires; 212-416-3216; albert.yoon@dowjones.com