What a difference a day makes for Big Oil. The oil industry scored a big victory on Friday, Nov. 15, as the U.S. EPA released a draft rule that—if allowed to stand—rolls back the highly successful renewable fuel standard (RFS). Following the announcement, which calls for our gasoline to include more oil and less biofuel next year, stock values surged for four of the “Big Five” oil companies—representing a $23 billion windfall in just one day.

“Big Oil’s big win on the draft rule for the renewable fuel standard led to an instant windfall for oil companies while consumers, American farmers and our troops are left holding the bag,” said Brad Woodhouse, president of Americans United for Change. “Big Oil hit the jackpot, but we are risking a huge slowdown in the development of next-generation biofuels that are our best hope for reducing America’s dangerous dependence on foreign oil.”

The Big Five oil companies reaped a combined $23 billion windfall, and the value of their outstanding shares increased by an average of more than 2 percent in a single day. This increase was about four times better than the performance of the Dow Jones Industrial Average and the S&P 500 over the same period between the closing bell the day before the announcement (Nov.14) and the opening bell on the next day of trading after the announcement (Nov. 18).

Meanwhile, an independent index of ethanol and biofuel stocks has fallen by more than 6 percent following the release of the draft rule. This is a very bad sign for the future of American leadership in clean, renewable biofuel, but it is a predictable market response to the draft proposal. If Big Oil gets its way, the steady rise in American biofuel use will be reversed next year, with less biofuel used in 2014 than in 2013.

Even though wholesale prices of ethanol are 60-80 cents cheaper than wholesale gasoline prices, Big Oil continues to falsely claim that the RFS requirement to use more of the inexpensive, clean, American made ethanol raises gasoline prices. Contrary to their argument, however, the announcement hasn’t brought any relief to American consumers at the gas pump—gas prices are actually slightly higher than before the announcement. The only winners are the oil companies who just reaped $23 billion while putting a choke hold on their only potential competition. (Gas price data from the AAA Fuel Gauge Report).

Here’s a breakdown of the Big Five oil companies’ increase in total market capitalization from the close of market Thursday, Nov. 14, to opening on Monday, Nov. 18:

-Exxon: Up more than $12 billion

-Chevron: Up nearly $2.19 billion

-Shell: Up nearly $6.88 billion

-BP: Up more than $2 billion

-ConocoPhillips: Down more than $258 million