Sky Bet reported a "one-way flow of money" for the Amercian, amid rumours that he was quittng his post as USA coach.
They were into 1/3 by lunchtime, Bradley having started the day as big as 4/1 with Paddy Power, although the price had drifted back out to 4/6 by the evening.
Sky Bet's Tim Reynolds said: "We've only laid one side to this market today so it looks as if people are believe that Bradley will be named as the next Villa manager.
"He's now our worst result in the fieldbook so we'll be hoping that Randy Lerner looks elsewhere."
Other firms slashed their prices to odds-on, including bet365, but they also pushed Bradley back out to later in the day. They went odds-against at 6/4 - perhaps significant given they are a Midlands-based firm.
Their spokesman Steve Freeth explained: "There were nibbles for Bradley on Thursday night, but the real plunge happened around midday on Friday when his price dropped from 3/1 into 4/7 in a matter of minutes.
"It now appears that reports of him departing his USA post are premature, although we're still seeing money at 6/4 which suggest something could yet happen in the future."
William Hill's Graham Sharpe also remained sceptical.
"There have been rumours from the States that Bradley has been lined up for the job but his lack of experience of the English game could count against him," he said.
Bradley, who took the USA to the last 16 of this summer's World Cup, was the subject of an initial gamble on Monday in the hours after Martin O'Neill resignation.
However, he drifted out in the following days as money came for Sven-Goran Eriksson.
The Swede had drifted to 4/1 by lunchtime before being cut back into a best of 7/2.