How bookmaker price movement works

The most common driver of price movement is money. When meaningful bets come in on one side of a market, the bookmaker's exposure to that outcome rises — and the trader will shorten that price (and usually lengthen the other side) to discourage further bets and attract balancing money. The same happens in reverse for the side that's seeing little action.

The second driver is the rest of the market. Bookmakers watch each other constantly. If three operators have shortened a runner from $4.00 to $3.50, the remaining operators will usually move within minutes — even if they haven't seen unusual money on that runner themselves. That's why a single sharp move can ripple across the board very quickly.

The third driver is information: a late scratching at the dogs, team news in the AFL, weather at the cricket. These can move both sides of a market simultaneously, jolting the median and resetting the opening price as a reference point. From a tracking perspective, the most useful patterns are the ones that aren't tied to news — those are the moves driven by money, and they tend to leave a measurable gap between the leading and lagging operators for a few minutes before everyone converges.