Commercial mortgages at U.S. banks have been failing at the fastest rate in nearly 20 years, the Wall Street Journal said, citing its own analysis.

Losses on loans used to finance commercial spaces would possibly reach about $30 billion by the end of 2009 at the current rate, the article said.

The estimated $30 billion is based on financial reports filed by more than 8,000 banks for the first quarter, the paper said.

The commercial real-estate market, valued at about $6.7 trillion, represents 13 percent of the U.S.'s gross domestic product, according to the paper.