How often do -500 or more favorites lose?

[gordon gekko]

I was estimating around 20 - 25 % of the time.

[LT Profits]

AT LEAST 20% of the time.

[Ganchrow]

The implied probability of a true (zero-vig) line of -500 would be: 500 (500+100) ≈ 83.33%.

If we assume 3.226% vig (the approximate vig given a market of -500/+400), then the implied probability of the -500 line would be (1-3.23%)× 500 600 ≈ 80.65%.

Note that in many sports (MLB being a very notable exception) money lines are frequently slightly shaded in the direction of the favorite meaning money line favorites tend to lose less frequently than one would expect by chance alone assuming an unbiased market. Joseph Buchdahl discusses this phenomenon in Fixed Odds Sports Betting: Statistical Forecasting and Risk Management, an excellent read for the neophyte advantage bettor.

[SlickFazzer]

The implied probability of a true (zero-vig) line of -500 would be: 500 (500+100) ≈ 83.33%.

If we assume 3.226% vig (the approximate vig given a market of -500/+400), then the implied probability of the -500 line would be (1-3.23%)× 500 600 ≈ 80.65%.

Note that in many sports (MLB being a very notable exception) money lines are frequently slightly shaded in the direction of the favorite meaning money line favorites tend to lose less frequently than one would expect by chance alone assuming an unbiased market. Joseph Buchdahl discusses this phenomenon in Fixed Odds Sports Betting: Statistical Forecasting and Risk Management, an excellent read for the neophyte advantage bettor.

Thanks for the info!

[HedgeHog]

Since the original question concerned teams -500 and more, the losing % is probably much less, perhaps approaching 10%. Many lopsided favorites in college fb and bb that rarely lose the game itself.

[Arilou]

Betting the underdogs blindly on the moneyline doesn't work once you pay even a Pinnacle or Matchbook level of vig. The only sport where that may work is MLB and the favorites peak around -300, so you have a reasonable cap on the damage right there. Slick makes an excellent point, but the shading is most certainly not enough to go in blind (there is one corner case that MAY work, but it doesn't come up enough to know for sure and in any case it is no way to make a living) so the range left for you is pretty narrow.