U.S. equities rallied in the last hour of trading Wednesday, before retreating in the last few minutes, as rumors that a $600 billion International Monetary Fund Bailout of the European sovereigns was about to be announced swirled the market, only to be dispelled just before trading closed for the day.

The Dow Jones Industrial Average, the golden benchmark of U.S. equities, went from 12,135 points at 3:14 p.m. New York time to 12,257.41 a half-hour later, a gain of over 1 percent in 30 minutes. The average lost most of those gains subsequently, closing the day at 12,196.37.

The KBW Bank Index, a financial industry benchmark that tracks the equity movements of 24 leading U.S. banks, rose and fell even more sharply. That index went from 39.14 to 39.79 during the same half-hour period, a jump of 1.66 percent, before retreating to 39.64.

The market rally subsided as CNBC ran a headline noting an "IMF official" had confirmed no bailout plans existed.

Interestingly, the roller-coaster continued into the after-hours session. While they followed the ups and downs of the wider market in its last hour, shares of 5 of the 6 major U.S. banks: Citigroup, Wells Fargo, JP Morgan Chase, Morgan Stanly and Goldman Sachs, rose in after-hours trading. Shares of Bank of America were unchanged after the closing bell