Could someone explain to me how betfair work out there rule 4s when there is a non runner ? I understand the backer always comes of worse than the layer and that betfairs rule 4s will always be higher than they would be if you bet with a firm. But it looks to the backers on betfair get a rule 4 on the profit and the stake of there bet. If this is correct its very unfair and might be one of the reasons the markets are so weak in the mornings.