I recently started using Matchbook. It's great as I can find good arbs. But there is something I can't understand.
Today I find an arb in AFL match. Odds on matchbook were 2.19 and $667 were available for one part of arb. I put $478 at odds of 2.19. Bet obviously matched. As soon as bet matched, market went offline for 15 minutes for this match. At same time, market was available on Pinancle but odds there were 2.07.
After 15 minutes, market on this match again became available on Matchbook with same odds and same bet amount ($667) available to be matched. I again put $478 at odds of 2.19 on matchbook. Available amount to be matched reduced to $189. After about 10 seconds available amount again was $667. I again put $478. Again available amount to be matched reduced to $189 but after 10 seconds again became $667.
This happen like 6 times.
Was it some BOT from some customer who was putting exactly $667 amount to be matched or was it Matchbook itself seeding the market?
How you will explain this phenomenon?
I wouldn't exactly call it a "phenomenon". It is commonplace with sports betting exchanges, in the same way stock markets and other similar markets use market makers to get the action going. You'd be amazed at how much of exchange liquidity is from automated bots rather than individual people sitting at their computers manually laying your bets.
All exchanges to varying degrees seed their markets, either using their own people or external market makers, or a mixture of both, with most bots pegged to Betfair's price.
Although it may say $667 available, as long as Betfair's price doesn't change during the time you are placing your bets, the bot will probably lay you thousands at that price if you wanted to bet that much so don't always take the headline amount available on the site as the maximum you can bet on that selection on that price at that time.
The more you use exchanges, the more you will get the feel of a market and be able to tell to a high degree of accuracy whether a bot is at work or not.