Some of the biggest banks and investment firms on Wall Street were among those that received minutes of the Federal Reserve's latest policy meeting 19 hours before the market-sensitive document was released.

The Fed said Wednesday that a staff member in its congressional liaison office accidentally released minutes of a March 19-20 policy meeting Tuesday afternoon to many of his contacts, including Washington representatives at Goldman Sachs Group Inc., Barclays Capital, Wells Fargo & Co., Citigroup Inc. and UBS AG. Also...