Estimates to recapitalize U.S. banks: $500 billion to $3.6 trillion

But without a cure for the problem of bad assets, the credit crisis that is dragging down the economy will linger, as banks cannot resume the ample lending needed to restart the wheels of commerce. The answer, say the economists and experts, is a larger, more direct government role than in the Treasury Department’s plan outlined this week…

Mr. Roubini’s numbers may be the highest, but many others share his rising sense of alarm. Simon Johnson, a former chief economist at the International Monetary Fund, estimates that the United States banks have a capital shortage of $500 billion. “In a more severe recession, it will take $1 trillion or so to properly capitalize the banks,” said Mr. Johnson, an economist at the Massachusetts Institute of Technology…

Still, these numbers are all based on estimates of the value of complex mortgage-backed securities in a very uncertain economy. “At this moment, the liabilities they have far exceed their assets,” said Mr. Posen of the Peterson institute. “They are insolvent.”