US regulators have asked Goldman Sachs, Merrill Lynch, UBS, JPMorgan Chase and other Wall Street banks to provide information on how they sold auction rate securities as part of an informal probe into the beleaguered market for the short-term bonds.

The industry-wide action by the Securities and Exchange Commission and Financial Industry Regulatory Authority underlines the watchdogs’ concerns at the sudden seizing up of trading in securities that were once considered almost as safe as cash.