Five of the largest credit unions in the U.S., including the U.S. Central Federal Credit Union have reported large losses on mortgage securities, according to the Wall Street Journal.

Those named include Western Corporate Federal Credit Union, Members United Corporate Federal Credit Union, Southwest Corporate Federal Credit Union, and Constitution Corporate Federal Credit Union.

While the losses suggest the housing crisis has spread to some of the more risk-cautious institutions, the federal regulator presiding over credit unions said these losses may well disappear when mortgage markets become more stable. The regulator also said that the credit unions have enough capital, according to the Journal.

The affected credit unions reported $5.7 billion of “unrealized" losses at the end of May this year, according to the Journal. Unrealized losses occur even when a security hasn’t been sold, when the market value of a security drops. According to the Journal, the losses of the credit unions are enough to wipe out the next worth of each of them, given that their negative equity is $2.9 billion and that their debts exceed the market value of their assets.

Commercial banks and financial firms nationwide have taken more than $300 billion worth of writedowns since the credit crunch began.