Moody’s Investors Service has put six U.S. banks on review for potential credit rating downgrades, following the collapse late last week of Silicon Valley Bank.

The credit rating firm late Monday also put Signature Bank, which failed Sunday, into deep into junk territory, according to CNN.

Moody’s warned it could issue similar downgrade for First Republic Bank, Zions, Western Alliance, Comerica, UMB Financial and Intrust Financial.

Moody's cited the "extremely volatile funding conditions" for some U.S. banks exposed to the risk of a run of customers withdrawing deposits, CNN also reports.

The firm made the changes after shares of regional banks suffered trading losses Monday, despite the federal government's stepping in to ensure depositors would have access to their money.