The over/under on Kansas City Chiefs quarterback Patrick Mahomes' rushing yards in Super Bowl LIV was one of the most popular prop bets offered at sportsbooks around the nation, and it went down to the final possession.

Mahomes' over/under rushing yards opened as low as 27.5 and was bet up to as high 36.5. Mahomes had 44 yards entering Kansas City's final possession. With the Chiefs leading 31-20 and 57 seconds remaining, Mahomes kneeled on three straight plays, losing 15 yards. He finished with 29 yards rushing, a costly outcome for bettors.

"That was close to a six-figure swing [in favor of the house]," said Jeff Davis, director of trading for Caesars Sportsbook.

Out of the hundreds of proposition wagers offered by William Hill U.S. sportsbooks, more money was bet on the over on Mahomes' rushing yards than was bet on any other market. Seventy-five percent of the bets and 68% of the money wagered on prop was on the over.

Sportsbook PointsBet said there was more than twice as much money bet on the over on Mahomes' rushing yards as was bet on the under.

"[It] cost bettors for sure," Patrick Eichner, communications director for PointsBet, told ESPN on Sunday.

PointsBet elected to refund all bets on Mahomes over 30.5 rushing yards, saying on Twitter that "if there's been a worse beat on a prop than this one, feel free to let us know!"

Earlier in the week, FanDuel also reported lopsided action on the over on Mahomes' rushing yards. "We've taken a hell of a lot of bets on that market," John Sheeran, director of trading for FanDuel, told ESPN on Friday. "In fact, our handle is nearly three times as much as what's bet on his passing yards, which is really interesting."

The Chiefs rallied from a 20-10 deficit in the fourth quarter for a 31-20 win over the San Francisco 49ers, covering the 1.5-point spread in a game that stayed under the total.

Sportsbooks were reporting big wins from the game. Davis of Caesars called the outcome a "monster" for his book.