Bank of America Corp. is placing a moratorium on all foreclosure proceedings and sales across the U.S. amid mounting political pressure on big U.S. banks to examine foreclosure-documentation problems.

The nation’s largest bank by assets is the first financial institution to stop all foreclosure actions amid revelations that the banking industry had used “robo-signers,” people who sign hundreds of documents a day without reviewing their contents, when foreclosing on homes. Bank of America, J.P. Morgan Chase & Co. and Ally Financial Inc. last week postponed foreclosures in 23 states where a court’s approval is required to foreclosure on a home.