Betfair trading is pairing a back and a lay on one selection on the Betfair exchange, placed at different times, so the price move between your two bets sets what the trade makes or loses. Back a runner for $40 at $4.60, lay it at $4.20 after it shortens, and a lay stake of $43.81 leaves $3.81 whichever horse wins, before commission (hypothetical prices).
Online in Australia, a sports trade has to be opened and closed before the event starts. Everything here happens before the jump in racing and before the game starts in sport, and every price is hypothetical.
How a trade locks in a result
A trade is two bets on one selection in one market: a back and a lay at different prices. The exchange settles both together, so the gap between the two prices decides the result. Trading on a betting exchange runs in two directions, and on team and player markets the same method is usually called sports trading.
Back first, lay lower
Example: hypothetical prices, not a real race. You back Runner 4 for $40 at $4.60. Twenty minutes before the jump it has firmed to $4.20, and you lay it to close the trade.
The back wins 40 x (4.60 - 1) = $144 if Runner 4 wins. Two ways to close:
| Closing lay at $4.20 | If Runner 4 wins | If any other runner wins |
|---|---|---|
| $43.81, the same result either way | 144.00 - 140.19 = +$3.81 | -40.00 + 43.81 = +$3.81 |
| $40, everything left on Runner 4 | 144.00 - 128.00 = +$16.00 | -40.00 + 40.00 = $0.00 |
The equal-result stake is 40 x 4.60 / 4.20 = $43.81, with a liability of 43.81 x 3.20 = $140.19. Making every outcome equal is greening up, and how to green up covers the formula, partial closes and closing at a loss.
Lay first, back longer
The mirror trade profits from a drift. Before a match starts, you lay Team A for $60 at $1.80, a liability of 60 x 0.80 = $48. Team news pushes Team A out to $2.00, and you back it for 60 x 1.80 / 2.00 = $54. If Team A wins: -48 + 54 x 1.00 = +$6. If it does not: +60 - 54 = +$6.
If either price had moved the other way, the same closing bet would lock in a loss. A trade going against you has no good exit, only smaller and larger losses, which is why the exit price and the stop price are set before the opening bet.
Risk: Betting involves risk. A locked result holds only if both bets are matched at the prices shown and the market settles normally. A price that moves against you locks in a loss just as easily, and there is no guarantee of profit. See responsible gambling for limits and support.
Sports trading in Australia stops at the start
Under the Interactive Gambling Act 2001, a bet on a sporting event, or on something that happens during it, is in-play betting if it is placed, made, received or accepted after the event has begun (s 10B). Online betting on sport is allowed only before the event begins (s 8A(3)), and only through a provider with a licence from an Australian state or territory (s 15AA).
ACMA, the regulator that enforces the Act, includes in-play betting on sporting events in its list of online services banned for people in Australia. A trade is two bets, so the rule applies to each half: an online sports trade has to be opened and closed before the game starts. In-play betting in Australia sets out the rule in full.
Trading guides written for other countries often describe trading during a match. For sport that is not available online here, and an offshore site offering it is an illegal service whose customers lose Australian protections, as ACMA's warning on illegal operators explains.
Whichever exchange you use, ACMA's register shows the licence holder and licensing authority for each licensed interactive wagering provider. Betfair Pty Ltd is on it, with the Northern Territory's wagering regulator as its licensing authority (checked 6 October 2026). Is Betfair legal in Australia explains what that entry covers. Bookmaker names are trade marks of their owners. B337 is not affiliated with them.
Racing trades end at the jump
Every racing trade on this page is closed before the jump, which gives it a fixed deadline. The money in an Australian race market on the exchange tends to grow towards the jump. The amount differs from meeting to meeting and race to race, so a market that is busy on one race can be thin on the next. Pre-race trading covers when that money arrives and how to read it.
Three things follow for a trader:
- The spread. The back lay spread is the gap between the best back price and the best lay price. Early prices can sit several ticks apart (a tick is the smallest price change the ladder allows at that level), and a trade opened across a wide gap starts behind. Market makers, traders who keep offers on both sides, are part of what narrows it.
- Timing. Your closing bet needs someone to take it before the jump, when prices can move fastest.
- The deadline. A trade you have not closed by the jump stands as an ordinary bet. If the closing lay on Runner 4 is not matched, you hold a $40 back at $4.60: +$144 if it wins and -$40 if it loses, before commission.
Commission and the cost of a trade
Commission is charged on your net winnings in a market at a rate the exchange sets, so a trade that closes ahead pays it and one that closes behind pays none. The rate, and any extra charges the exchange's terms place on some winning customers, are the exchange's to set and change, so treat them as inputs. At an illustrative 7%:
| Trade | Before commission | After 7% commission |
|---|---|---|
| Runner 4, equal result | +$3.81 | 3.81 x 0.93 = $3.54 |
| Runner 4, all on the runner, if it wins | +$16.00 | 16.00 x 0.93 = $14.88 |
| Team A, equal result | +$6.00 | 6.00 x 0.93 = $5.58 |
Because only winning trades pay, commission weighs most on small, frequent wins. A trader whose wins and losses are the same size needs a win rate of 1 / (1 + 0.93) = 51.8% at 7% to break even. Over 100 trades of $10 that win 50 and lose 50, the trades net $0 and commission costs 50 x 10 x 0.07 = $35.
The spread is the other cost. In a market showing $5.00 to back and $5.40 to lay, backing $50 and closing straight away with a lay of 50 x 5.00 / 5.40 = $46.30 loses about $3.70 whichever runner wins. Exchange trading strategies covers how scalping and swing trading deal with both costs, tick by tick.
Why a trader needs a tested edge
No official figure counts how many exchange traders make a profit. Every matched bet has a backer and a layer, and commission comes out of whichever side finishes a market ahead, so everyone using the exchange, taken together, finishes behind by what the exchange charges. A trader's profit has to come out of other people's losses, and a trader without a tested edge should expect to lose.
Scamwatch, run by the ACCC, warns about sports investment schemes, including ones sold as sports trading (checked October 2026). Is exchange trading profitable costs a month of trades line by line, automated competition included.
Risk: Betting involves risk. Trading is betting: each half of a trade can lose, a fast market can move past your stop before you close, and there is no guarantee of profit. See responsible gambling for limits and support.
How to place a trade on Betfair
- Set the deposit limit on your exchange account before you start, and decide the most you will lose in a session.
- Choose a market with money on both sides close to the price: a narrow spread, and plenty already matched compared with your stake.
- Write down the direction, the entry price, the exit price and the stop price before you place anything.
- Place the opening bet: a back if you expect the price to shorten, a lay if you expect it to drift.
- When the price reaches your exit or your stop, place the closing bet on the same selection on the other side, sized for the result you want.
- Check that both bets are fully matched, and that nothing is left waiting with a jump setting you did not choose.
- Finish before the start: before the jump in racing, before the game starts in sport.
The lay betting hub covers laying, liability and commission in more depth.
What can go wrong with a trade
- A part-matched opening bet. If only $25 of the $40 back at $4.60 is matched, the equal close is 25 x 4.60 / 4.20 = $27.38. Laying the planned $43.81 instead leaves a new bet against the runner: -$50.19 if it wins, +$18.81 if it loses.
- Closing on the wrong side. Backing $43.81 at $4.20 instead of laying it adds to the position: +$284.19 if Runner 4 wins, -$83.81 if it loses.
- A scratching. The exchange's scratching rule can reduce the prices of matched bets on the other runners, so the two halves no longer cancel exactly.
- A voided market. If the exchange voids the market under its rules, both halves go with it.
- Letting a loss run. A $40 back at $4.60 that drifts to $6.00 instead of firming costs 40 - (40 x 4.60 / 6.00) = 40 - 30.67 = $9.33 to close for an equal result, and more if it keeps drifting.
What B337 does and does not do for traders
B337 does not trade or place any bet on the exchange, so both halves of every trade here are yours to place in your exchange account.
Its Terminal lines up Betfair back and lay with prices from 40+ bookmakers across racing and sports, plus flucs, which shows where bookmakers and the exchange disagree before you open a position. It reads prices on a repeating cycle, not every tick, so it is not a trading ladder: confirm every price on the exchange before you bet.
Risk: Betting involves risk. A price shown on the Terminal can trail the exchange, a trade can be left half matched at the jump, and past results are no guarantee of future results. See responsible gambling for limits and support.