While Merrill will now have quick access to Bank of America's deposits, traditional commercial banks are being pummeled by rising delinquencies and defaults in commercial and consumer loans.

Such an outcome — a classic 'V-shaped' recovery marked by a quick bottoming out and a lasting rebound — would enable stocks and other assets to keep rising in the second half of the year.

The greater acceptance of debt allowed private-equity firms and hedge funds to bet on rising asset prices with borrowed money, which is a quick route to riches when all goes well.