Is an Odds-On Favourite More or Less Likely to Win the More Horses There Are in a Race?

If you happened to have purchased Eddie’s ‘Odds-On Winners’ strategy guide, then you’ll know that it is possible to make a profit even by backing horses that are at extremely short odds. After all, a win is a win, and when you are getting value with your selections, as is the case with Eddie’s guide, long-term success is likely.

However, it is obvious that backing odds-on favourites blindly is a losing strategy. For this article, I will use SP odds which means an odds-on horse is anywhere from 1.01 to 1.91. However, I am also using Betfair ROI because it is almost always better than its SP equivalent. 

In the UK since the beginning of 2014, 60.37% of the over 7,700 odds-on favourites have won the race, but your SP loss would be 3.7%, and the Betfair loss would be 1.81%.

In this article, I aim to discover whether an odds-on favourite is more or less likely to win when there are more horses in the race. There are two schools of thought on the subject. First, races with few horses might be run at a slower than normal pace which may not play into the hands (hooves) of the favoured horse.

The second school of thought says that races with a greater number of runners can cause issues. There is a bigger risk of a runner finding form on that particular day, or the horse could get boxed in. In National Hunt races, a horse could fall in front of a favourite, and so on. 

Races With 2-10 Runners

The data I am using comes from UK races since the beginning of 2014. You would not expect there to be so many events with 2-4 runners, but they comprise over 20% of all races. 

It may come as a surprise that the strike rate is so low, but in many of these events, the gap in odds between the odds-on favourite and the second favourite is often fairly small.

When you break it down into race code, it is Flat races that come out on top with a minimal Betfair profit of 1.12%. If you focus on Flat Handicap races only with 2-4 runners, you end up with a nice surprise:

An overall profit of more than 10% is significantly better than what you’re getting from your savings account! It is an angle that has only been profitable since 2016 however. If you focus on the last three years, the profit increases to more than 21%. It remains to be seen whether it is a betting strategy that will work in the future.

Next up are races with 5, 6 or 7 runners. 

As you can see, over 40% of races with an odds-on favourite have this number of runners. In fact, races of 2-7 runners comprise around 65% of all races with an odds-on runner. The win rate falls a little, but the loss decreases.

When I looked at National Hunt handicap races with 5-7 runners only, there was extremely good news. 

As well as enjoying a higher strike rate, your profit since the start of 2014 would be almost 11%. Moreover, each of the last five completed years has been profitable to some degree, ranging from 1.41% in 2016 to 20.28% in 2018. The average A/E is 1.08, so you are also getting value for money with these bets. 

Here is what happens in all races with 8-10 runners:

As expected, the win rate falls, and your losses increase to almost 3%. In this instance, All-Weather handicap races are what you should be looking for:

There are not that many races, but a profit of 15% makes them worth the wait. 2018 is the only year with a loss, and the A/E value is 1.11. Incidentally, at the time of writing, all four odds-on favourites in these races have won in 2019. 

Races With 11+ Runners

The strike rate is set to tumble but does this equate to further losses. Let’s look at races with 11-15 runners:

The strike rate is only marginally lower than in races with 8-10 horses, and you also sustain minimal losses. Once again, All-Weather handicap races are a source of profit:

The downside is few races, but you would have enjoyed a profit every year since 2014. Flat non-handicap races are also a good option:

In this instance, you would only have lost money in 2017, which was admittedly a very bad year with losses of almost 20%.

Here are what things look like in races with 16+ runners:

It is not even worth looking at such races because there are so few, and you would lose money in any case. 

Final Thoughts

Experienced horse racing punters reading the article knew that the answer to the title question was ‘yes.’ The strike rate of odds-on favourites inevitable falls the larger the field. The real issue is whether you can find value in these races, and the answer to that is also ‘yes.’

There are several micro angles worth exploring including:

• Flat Handicap races with 2-4 runners.
• National Hunt handicap races with 5-7 runners.
• All-Weather handicap races with 8-15 runners.
• Flat non-handicap races with 11-15 runners.

In isolation, none of these micro-angles provide enough potential bets. But when you combine them all, it averages over 150 possible bets each year, or 12-13 per month. Obviously, you should still try and form read the race to avoid backing a false favourite, but this is a decent bank builder with a good strike rate, and relatively short losing streaks.