An internal investigation into the accounting scandal that has caused a crisis of confidence at Freddie Mac is expected to be completed by August 1 and will be published as soon as it is received, the company said.

The investigation centres on how Freddie Mac, one of the two giant mortgage finance providers, understated earnings by up to $4.5bn between 2000 and 2002. It is expected to detail the activities that led to the company's acknowledgement of "earnings management" designed to reduce the volatility of its future financial results.