Freddie Mac could receive between $2.2 billion and $3.4 billion in more profits from forcing lenders to buy back "a significantly larger" number of soured mortgages, according to the Federal Housing Finance Agency Inspector General.
Up to $1.2 billion in new profits could go to the GSE this year alone.
The FHFA IG said the estimates are based on a review of 350,000 more loans than before.
"Freddie Mac has been carefully monitoring its own activities, modifying its plans, and updating its estimates of results based on its month-to-month experience in reviewing nonperforming loans," the inspector general said in a report released Thursday.
FHFA Deputy Inspector General for Evaluations George Grob said in a letter to the watchdog that the agency was developing plans to align how both Freddie and Fannie Mae review repurchase requests.
The "contract harmonization initiative" is expected to launch at the end of 2012, Grob wrote.
Lenders had to buy back $1.2 billion in problem home loans from Freddie in the second quarter. Another $2.9 billion in repurchase requests are still outstanding as of June 30, according to its financial filing.
The FHFA IG raised concerns one year ago about repurchase oversight at Freddie, when its regulator began monitoring how the GSE would manage repurchase claims in a $1.35 billion settlement struck with Bank of America (BAC) in January 2011.
Up to 100,000 mortgages originated in just 2006 could have been reviewed under broader criteria, the watchdog found. Freddie was reviewing only loans that defaulted in the first two years after origination. One senior examiner said most loans sold to Freddie during the housing boom defaulted after this time period, leaving many loans overlooked.
In October 2011, less than a week after the report was released, Freddie senior management proposed going after more loans, and the FHFA gave the go-ahead. The GSE alerted its lenders in March.
The inspector general said the final results of the expanded review would not be realized until next year or even until 2014. Freddie has drawn more than $72 billion from taxpayers since entering conservatorship in 2008. The Treasury Department said in August it would end the 10% dividend payments and begin sweeping all future profits back to taxpayers.
On Tuesday, the FHFA released repurchase guidance on loans the GSEs buy starting Jan. 1. For mortgages financed after that date, the GSEs will release repurchase risk once the borrower makes three years of consecutive payments.