A horse racing spread betting market that predicts the aggregate total of the winning margins of each race at a meeting. The maximum winning distance for a Flat race is set at 12 lengths while for a National Hunt race it is 30 lengths. This also applies should only one horse complete the race.
Distances under a length are recorded as follows: Short head = 0.1 of a length, head = 0.2 of a length, neck = 0.3 of a length, half a length = 0.5 of a length, three-quarters of a length = 0.75 of a length.
For example, at a jumps meeting at Cheltenham, Sporting Index might offer a spread on total winning distances of 70-75. You might decide to place your spread bet high at 75 for £5 per length.
In the end the winning distances made up at 82 lengths. If you had gone high at 75 you would have won seven times your stake: (82 - 75 = 7) x your stake (£5) = £35. But if winning distances had made up at just 67 lengths, the same bet would have lost you 8 times your stake (67 - 75 = -8) x your stake (£5) = -£40.