WASHINGTON -- The U.S. government is expected to take stakes in nine of the nation's top financial institutions as part of a new plan to restore confidence to the battered U.S. banking system, a far-reaching effort that puts the government's guarantee behind the basic plumbing of financial markets.

To kick off Tuesday's expected announcement, the government is set to buy preferred equity stakes in Goldman Sachs Group Inc., Morgan Stanley, J.P. Morgan Chase & Co., Bank of America Corp. -- including the soon-to-be acquired Merrill...