5.30 Rule 4

2.36 x .75= 1.77

Not quite Dave1357. Thats including the stake. To apply a 25% deduction the correct calculation  is 1.36 x 0.75 = 1.02

The BF RF does include the stake,JRAS

Taking that logic further, if a long odds on favourite is withdrawn and there is an 75% R4 you could get less than your stake back. r4 should not include the stake. I will have a look at BFs R4 rules

It was introduced to encourage Layers to the Exchange

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Rule 4 covers the situation where a horse is withdrawn from a race, the odds for all bets placed on remaining horses are adjusted to account for the non-runner(s).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.

In the picture above this which it will not allow me to cut and paste, it states that Rule 4 is deducted as a percentage of winnings. ie. it does not include the stake

Tattersalls Rule 4 is for bookmakers.

Betfair betting exchange is not a bookmaker and uses its own Reduction Factor.

got to be a fishing thread - 22 years on betfair and he doesn't understand that the exchange doesn't operate rule 4 but implements a reduction factor

unhook me please.

Anybody got a disgorger

You think thats bad, I placed a bet yesterday with required odds of 1.72.  There was a withdrawel with a reduction of 53.3%, my bet now became 1.01. So I have a 50 euro bet to win which gives me 50cent profit if it wins.  I asked Betfair about this since no right minded person would back a horse at 1.01 but that is correct to their calculations.  If it was with a bookmaker it would have a new odds of aprox 1.35.  This exposes the backer to extreme odds...so much so that i would question the logic of using Betfair