What is Rule 4?

• Rule 4 covers the situation where a horse is withdrawn from a race, the odds for all bets placed on remaining horses are adjusted to account for the non-runner(s). This is because less horses in a race increases the probability of each remaining horse winning. A Rule 4 is normally expressed as x pence in the pound, and is an industry-wide rule.
• If you'd like to find out more information about non-runners, see our article here.

Have you got an example?

• You have elected to bet on Horse A @ 5/1 in the 2.30 at Ascot. There are only 3 runners in this particular race and later on in the day, Horse B @ 7/4 unfortunately has to withdraw from the race.
• The race now becomes a 2 runner race and immediately your horse's chance of winning have increased from 1 in 3 runners to 1 in 2 runners. Once the non-runner is official we will revise the race at the earliest opportunity with new odds for the 2 remaining runners. Therefore with this in mind, the 5/1 taken earlier in the day is now no longer a fair reflection of Horse A's chances and some form of reduction is needed to compensate.

Another horse in the race was a non-runner, why has my win paid out for less?

Sportsbook treats non-runners the same as every other bookmaker, by applying a 'Rule 4'. The 'Rule 4' deduction values are industry standard, deductions are measured by a number of pence in the £, based on the odds of the horse at the point of withdrawal.

For bets where a price is taken, the application of Rule 4(c) will be determined by the last Betfair price available at the time the relevant horse is withdrawn.

If you'd like to find out more information about non-runners, see our article here.

How do I calculate a Rule 4 deduction?

Calculating Rule 4 can be tricky-and realistically you're not expected to do it yourself! It all depends on the price of the non-runner and the strength of the field. However, as a general rule this table explains the basic Rule 4 deductions...

• If there are two or more withdrawals in one event, the deduction will not exceed 90p.
• If the price of a withdrawn selection is not quoted in the above table, then Rule 4(c) will be applied at the next highest price quoted. For example 21/5 would be classed in the 9/2 bracket for Rule 4 purposes.

Sportsbook Example:

If you had a bet on a horse for £10 at 10/1 that went on to win, but in the same race the favourite (priced at 2/5) pulled out, your total return would be:

• Pre 'Rule 4'

£10 x 10 = £100 (profit pre 'Rule 4')

£100 + £10 = £110 (total return pre 'Rule 4')

• Post Rule 4

£100 less 70% (70p in the £) = £30 (profit post 'Rule 4')

£30 + £10 = £40 (total return post 'Rule 4')

This is different to the Exchange, which applies a separate non-runner reduction calculation.

Exchange:

I bet on a non-runner, what happens to my bet on Exchange?

• Bets placed on Future Racing/Ante Post will be settled as a losing bets.
• Bets placed on Day of the Race markets will have their stakes returned once the non-runner is declared. If you'd like to find out more information about non-runners, see our article here.

My bet was a winner, what are non-runner deductions?

Non Runner deductions (Rule 4) are pretty much the same on Sportsbook as they are on the Exchange. The difference is that the reduction factor will be applied to the prices of all matched bets, for both backers and layers. This is to ensure that layers are not unfairly treated and exposed to large liabilities when the chances of other horses winning have improved. The reduction factors are designed to be fair to both backers and layers.

How is the reduction factor applied on Exchange?

When a bet is struck, the price that it was matched at will be recorded on the system. If there is a subsequent withdrawal (non-runner), we will reduce the matched price by the reduction factor of the withdrawn horse.

If you want to calculate the new price once a reduction factor has been applied, this is how:

(Decimal odds / 100) x reduction factor of non-runner = amount to reduce original price by

Subtract this amount from the original price to calculate the new price.

• You matched a back bet on the horse 'Diamond Night' for £10 @ 8.6.
• Your liability is £10.
• A horse in the same race is now withdrawn with a reduction factor of 16.2%

 
(8.6 / 100 ) x 16.2 = 1.39 (this gives the amount to be reduced from the original price)

Example Layer:

• You matched a lay bet on the horse 'Diamond Night' for £10 @ 8.6.
• Your liability is £76.
• A horse in the same race is now withdrawn with a reduction factor of 16.2%

If the reduction factor for a withdrawn horse is less than 2.5%, then the price reduction is not applied, as the horse was not really a material runner and if withdrawn, the difference to the betting would be negligible.

The reduction factor work slightly different on 'Place' markets. Please view Exchange: How do reduction factors work on place markets?