Intrade market on the Republican primary. After Mitt Romney won New Hampshire and bounced to the top of the South Carolina polls, he climbed to over 90% on Intrade. When Newt Gingrich won South Carolina, Romney's Intrade odds plummeted.
Gingrich topped the Florida polls following his South Carolina victory. But Intrade investors did not simply flip the odds in his favor and give him as great a chance of winning the nomination as Romney had gotten following New Hampshire. At Romney's lowest point, on January 24 (before all of the pro-Romney polls started pouring in), he fell to less than 65%. Quite a drop from 90%, but not all the way to Gingrich's level.
By contrast, the Intrade market for the Florida primary took the poll numbers pretty much at face value. Romney, who had been rated over 90% to win Florida, fell to less than 40%, giving Gingrich a decent odds advantage. Evidently the investors understood the difference between winning Florida and winning the nomination: Even if Gingrich won Florida, they felt Romney would still have a firewall in later contests. However, it seems likely that if Gingrich won Florida, Romney's Intrade odds for the nomination would have fallen further, below Gingrich's.
The last several days have turned things around. New polls show Romney leading in Florida by nearly 10 points. Romney's strong performance at Thursday's debate (and Gingrich's weak performance) also made a difference. Romney's odds of winning the Florida Primary are back over 90%. His odds of winning the nomination are at 87%. If/when Romney wins Florida, his odds will probably match their earlier highs, perhaps reaching toward the 95% mark.
Romney's gain is Gingrich's loss. Today, his Intrade odds stand at 5.6%. Before Thursday's debate, he was trading at nearly double that. Ron Paul is at 3.4%. Rick Santorum can't catch a break--he is only at 1.9%. Intrade markets have started opening for the February contests, and Romney enjoys a substantial lead in each of these.