The online bookmaker were offering odds of 16/1 on the Denmark international heading to Villa Park before seeing a sudden run of bets on Tuesday night, prompting them to cut the price to 1/8.
Bendtner is available on a free transfer after being released by Arsenal this summer following 10 years with the north London club, scoring 47 goals in 171 appearances.
Hull and Crystal Palace are considered the main rivals to secure the 26-year-old’s services at 10/1 and 12/1 respectively, while a return to Sunderland, where he spent a season on loan during the 2012/13 season, is a 14/1 chance.
Sky Bet’s Chris Spicer said: “We had lacked a clear favourite in the market on Bendtner’s next club ever since he was released by Arsenal, with Hull the soft favourites initially.
“However, Villa have attracted nearly 90 per cent of all stakes now, with the majority coming in the last 24 hours including one three-figure bet at odds of 1/4.”