Chris Christie’s surprise endorsement of Donald Trump on Friday immediately set tongues wagging about what’s in it for him. After all, Mr. Trump has said of Mr. Christie that “there could certainly be a place for him” as his running mate.

Betting markets seem to think that there’s something to this idea. At Ladbrokes, the only major bookmaker betting on the No. 2 slot, Mr. Christie’s odds of being the Republican nominee for vice president were 8 to 1 before a few bets alerted it to the endorsement. The British oddsmaker immediately slashed the odds to 5 to 1, then 4 to 1, and after a flurry of more bets, has further cut Mr. Christie’s odds to 5 to 2. (If you find British odds a mystery, note that this translates to a two-in-seven, or 29 percent, chance.)

That said, in lightly traded markets like this, the bookmaker builds in a large profit margin, which exaggerates these probabilities. As such, it’s probably better to say that Mr. Christie’s chances are around 10 to 15 percent.