Bank examiners from the Federal Reserve and the Office of the Comptroller of the Currency are looking at the books of mortgage investors Fannie Mae and Freddie Mac, a person familiar with the situation said.

The examiners are working with the two companies' main regulator, the Office of Federal Housing Enterprise Oversight, or Ofheo, this person said. This joint effort to assess the financial condition of the two government-sponsored companies was first reported by the New York Times Web site late Monday.

Fannie and Freddie face sizable losses as defaults increase and home prices fall. That has caused a plunge in their share prices over the past few weeks, though the shares have recovered somewhat in recent days. Ofheo has said that the companies' capital remains above their regulatory minimums.

In light of the recent market turmoil, increased sharing of information among regulators is "prudent," Ofheo Director James Lockhart said in a statement late Monday.

A spokesman for Freddie declined to comment. Fannie representatives couldn't be reached for comment.

Earlier this month, the U.S. Treasury agreed to a package under which the government would provide loans or equity to Fannie and Freddie if they are unable to raise sufficient capital on their own.

Write to James R. Hagerty at bob.hagerty@wsj.com

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