David Nason, the U.S. Treasury's Assistant Secretary for Financial Institutions, told CNBC television that the Treasury executed final investment agreements with the nine banks on Sunday.
He declined to rule out capital injections for insurers and other companies but said there were significant questions about how such investments would work and whether they were needed for financial stability.
"We started with the banks because that's targeted to providing credit to the economy, but there are a lot of industries coming in saying they need federal assistance, so we're willing to listen to their asks," Nason said.