Grayson, who left Sunderland in October, had been 4/1 to take the reins at Bradford City.
Simon Grayson is now the odds-on favourite to become Bradford City's next manager, less than three months after leaving Sunderland.
Grayson had been 4/1 on Sky Bet's market, but has seen his odds shorten significantly to 5/6 on Wednesday afternoon.
As a result, the 48-year-old has leapfrogged Bradford scout Greg Abbott and former Stuttgart boss Hannes Wolf, who are now 8/1 and 2/1 respectively.
The Ripon-born boss, who has worked for Bradford's Yorkshire rivals Leeds United and Huddersfield Town, is also high on Sky Bet's market for the vacant Barnsley position at 2/1.
Sunderland sacked Grayson on Halloween, with the Mackems in the Championship's bottom three.
He had only taken the role in July, following four years at Preston North End.
Would the former Sunderland boss be a good appointment for Bradford?