The Super Bowl is annually the biggest betting event of the year in the U.S. This year, though, it may be eclipsed by a boxing match.
Kevin Bradley, the sports book manager of Bovada.lv, said betting on Mayweather-McGregor has been massive already.
“We knew this fight would be big, potentially even bigger than the Super Bowl, but now we are almost certain it will be,” Bradley said. “The recent trash talking and promotional tour is only encouraging bets and at this rate we cannot even imagine how much we will take on it. One thing is for sure though, we will need Mayweather huge. A McGregor early round KO as he promised would be a potential disaster and is partly a reason we are giving a great price on Mayweather at the moment.”
Bovada released a slew of wagering possibilities, but the odds on McGregor have dropped significantly. Mayweather is down to minus-500, while McGregor is now at plus-350.
Amazingly, a prop bet on whether Mayweather will be knocked down or out is only at plus-350. Mayweather is 49-0 and has only been down once in his career, and that came when he intentionally touched the canvas with his glove in the final round of a fight he was winning big because his hand was injured and he wanted a brief break.

Here are some other betting possibilities from Bovada:
Will Conor McGregor throw a kick in the match?
Yes      +1100   (11/1)
No        -6500   (1/65)
Will there be a point deducted?
Yes      +350     (7/2)
No         -600     (1/6)
Will both fighters be knocked down?
Yes      +600     (6/1)
No         -1600   (1/16)
Will either fighter be knocked down or out?
Yes      -375     (4/15)
No        +240     (12/5)
Will Floyd Mayweather Jr. be knocked down or out?
Yes      +350     (7/2)
No        -600     (1/6)
Will Conor McGregor be knocked down or out?
Yes       -300     (1/3)
No        +200     (2/1)
Total rounds
Over     9.5        +125     (5/4)
Under   9.5        -175     (4/7)
Will the fight go the distance?
Yes      +160     (16/10)
No        -230     (10/23)
Method of victory
Mayweather Jr. by KO, TKO or DQ                                          2/3
Mayweather Jr. by Decision or Technical Decision                   5/2
McGregor by KO, TKO or DQ                                                4/1
McGregor by Decision or Technical Decision                          10/1
Draw or Technical Draw                                                             50/1

source: sports.yahoo.com