Paul & Dave both have a point when it comes to arbing, although I believe the two issues are related.Before the advent of API, BOTS, automated prog.s (call em what you will) you could easily trade horse arbs on Betfair at 10/15% profit; assuming back bet placed first. eg. back £100 at 5.0 lay £110 at 4.5, profit = £10/£15. The auto. progs are soaking up all the price gaps, resulting in lots of trades making a few pence, sometimes pounds, but with a licence fee liabilty of £100 - £150 per month, not very lucrative.

With regards the horses it needs more imagination, such as backing the Racing Post Pricewise horse while the price is guaranteed by a bookmaker and then laying back on Betfair. Better still lay the horse you think must likely to be increased in price in the same race as the Pricewise selection (Bookies balance the book) and then bet back. Some people follow one of the big tipsters(winnigline, fantastic forecasts, etc. purely to arb the selection, their influence being so large it invariably drags a price down by a few points, sometimes a lot.

Other sports are another issue. Arbs often exsists between conventional bets and spread bets on the same market. Especialy 3 outcome events such as boxing, football, baseball etc. Arbs often exsist between spread firms on markets and for fear of being accused of colluding they keep them open for a while (obviously thet know they are there). Trouble is they severly reduce the stake they will accept (say £50.00 a point when normaly they would have gone £500. a point, shame :-(

I used to work a sort of arb on horses before Betting Exchanges were invented. The lay part being achieved with a Spread Bet. There is still some good milage in this system if operated with care; more on that later. I also invented a numerical way of spread betting greyhounds which can also make good money; more on that another time. There is a nice way to make virtualy guaranteed money on Black Jack with little risk (100/200% returns are common). At the moment I am working on a Poker system. Perhaps by all sharing we can compare experiances and refine some strategies ?
Richard...