Debt Reckoning: U.S. Receives a Margin Call

The U.S. is at the receiving end of a massive margin call: Across the economy, wary lenders are demanding that borrowers put up more collateral or sell assets to reduce debts.

The unfolding financial crisis -- one that began with bad bets on securities backed by subprime mortgages, then sparked a tightening of credit between big banks -- appears to be broadening further. For years, the U.S. economy has been borrowing from cash-rich lenders from Asia to the Middle East. American firms and households have enjoyed readily available credit at easy terms, even for risky bets. No longer.