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Who takes the other side of the bet?
A bookmaker is a party to the bet it accepts from its customer. A betting exchange brings together opposing customer offers: one side backs a selection and the other lays it. That changes whose position you must understand, how an offer becomes a bet, and what the amount labelled “stake” measures. It does not make the exchange risk-free or establish which service is suitable for you.
The example below follows one fictional matched bet from both customers’ perspectives. At decimal odds of 3.00, a backer’s stake of 20 monetary units corresponds to a layer’s liability of 40 units. Those are two different amounts at risk on the same bet, not two names for a 20-unit loss limit. Every amount in the examples is fictional; none describes an available price or a suggested transaction.
The UK Gambling Commission’s definitions and betting guidance provide the intermediary-versus-contract-party distinction in a Great Britain regulatory context. They do not determine the legal classification or availability of every product worldwide. An intermediary still has service, custody and other obligations; facilitating a bet does not mean having no responsibilities.
Back and lay refer to the same selection
To back “Team A wins” is to take the position that this selection will win. To lay that selection is to take the opposing position: Team A does not win. In a football market that includes a draw, laying Team A to win can therefore win on either a draw or a win by Team B, subject to that market’s settlement rules. It is not equivalent to backing Team B to win. Betfair’s lay-bet explanation illustrates this distinction.
- Backer: Team A wins
- The backer’s 20-unit stake can be lost if the selection loses. At odds of 3.00, a full win produces 40 units of profit before fees.
- Layer: Team A does not win
- The layer can lose 40 units if the selection wins. If it loses, the layer earns the backer’s 20-unit stake before fees.
- Exchange: matching intermediary
- Matching connects these opposing positions. This figure concerns the two customers’ bet, not the platform’s complete finances or obligations.
Here, D is decimal odds, S is the backer’s stake, and L is the layer’s liability. For a simple matched bet with full-win or full-loss settlement, L = S × (D − 1). Thus 20 × (3 − 1) = 40. Smarkets’ liability guide also explains that a lay interface may display the backer’s stake or the liability, depending on its display setting. Read the field’s definition before treating its number as the amount you could lose.
Follow both accounts through settlement
The next table keeps the two customers separate. It assumes the whole 20-unit back stake has matched at 3.00, with no other bets in either customer’s market account. Positive figures are profit and negative figures are loss, relative to the money each customer put at risk. They are not gross returns.
| Settlement outcome | Backer before fee | Layer before fee | Backer after fee | Layer after fee |
|---|---|---|---|---|
| Team A wins | +40 units | −40 units | +38 units (2-unit fee) | −40 units (no fee in this model) |
| Team A does not win | −20 units | +20 units | −20 units (no fee in this model) | +19 units (1-unit fee) |
If Team A wins, the backer’s gross return before fees is 20 × 3 = 60 units: the original 20-unit stake plus 40 units of profit. Under the fictional fee, that return becomes 58 units, including the returned stake. If Team A does not win, the layer’s 20-unit profit is distinct from the release of the layer’s own 40 units of liability. Counting released money as additional profit would overstate the result.
The two customers’ profits and losses sum to zero before fees. After this model’s fees, they sum to −2 units when Team A wins and −1 unit when it does not. These are opposing accounts on one bet, not a recipe for one person to earn both sides’ winnings. The 5% rate and fee rule are invented for this calculation, not a quoted charge.
This two-outcome table excludes voids, errors, dead heats, partial settlement, non-runners, rounding, tax, currency conversion and other charges. It is not a complete loss limit for every product or account. The selection and applicable rules determine whether an actual result fits either row.
A submitted offer is not a fully matched bet
An exchange price needs an opposing offer willing to match it. A displayed price or submitted request does not establish that the whole amount has been accepted. Betfair’s matching guide distinguishes unmatched, partially matched and fully matched offers.
| Part of the request | Back stake | Corresponding lay liability | What the number establishes |
|---|---|---|---|
| Matched portion | 8 units | 8 × (3 − 1) = 16 units | This portion creates the modelled matched exposure; the layer’s potential profit is 8 units before fees. |
| Still unmatched | 12 units | No matched liability from this portion yet | The open portion may match later unless it is cancelled or lapses under the relevant rules. |
The 16-unit liability describes only the matched 8 units. It does not establish a final limit while the other 12 units remain open. Different fills can also occur at different prices, requiring a calculation for each fill. A cancellation request is not proof that cancellation completed before another match; a matched bet cannot simply be treated as cancelled because its unmatched remainder was cancelled.
Smarkets’ time-in-force documentation describes product-specific ways an unfilled portion can remain open or expire, while its terms qualify cancellation and matching. These examples do not establish a universal order setting or promise that reserved funds are immediately released. An unmatched offer intended to offset an existing bet does not remove that bet’s exposure.
Name the commission base before applying a rate
“5% commission” is incomplete without a base. Betfair’s commission explanation uses net market winnings within its applicable fee arrangements. That differs from charging a percentage of every winning bet or of every stake.
Consider a separate fictional account with two settled positions in the same market: one earns 40 units before commission and the other loses 15. Its net market profit is 25 units. Under the hypothetical 5% positive-net-market-profit rule, the fee is 25 × 0.05 = 1.25 units, leaving 23.75 units. This example combines positions within one account; it does not combine the two opposing customers in the earlier table.
| Calculation | Fee | Profit after fee | Does it follow the assumed rule? |
|---|---|---|---|
| Net the positions first: 40 − 15 = 25 | 25 × 5% = 1.25 units | 25 − 1.25 = 23.75 units | Yes: positive net market profit is the base. |
| Charge the winning position alone: 40 × 5% | 2 units | 40 − 2 − 15 = 23 units | No: this uses a winning-position base instead. |
The first row is correct only under the stated fictional rule. Smarkets’ commission FAQ supplies an important counterexample: some tiers charge per matched, settled bet, including losing bets. A “no commission on losses” statement therefore cannot be applied to every exchange account. Rates, packages, discounts, events, regions and additional charges also vary; consult the applicable schedule rather than carrying this example’s 5% into a real account. Betfair’s charges page likewise has scoped arrangements.
Compare the contract and rules, not just the quote
A bookmaker quotes terms for a bet it accepts as counterparty. An exchange quote depends on opposing matching liquidity; participants can include liquidity providers and automated systems, not just individual recreational customers. Neither mechanism alone guarantees a better price, sufficient liquidity, a fill or a safer outcome. This guide supplies no platform ranking.
Before two numbers can be compared meaningfully, their selections and settlement basis must agree. “Team A wins” may depend on whether a market covers regular time, extra time or another defined period. Even one brand can use different rulebooks: Betfair’s Exchange rules distinguish the Exchange from its Sportsbook. Rules for abandonment, errors, dead heats and voids cannot be inferred from the brand name or the simple formula.
These operator documents are examples of mechanisms and contractual differences, not recommendations or evidence that a service is available to you. This guide does not determine whether your age or location permits participation, whether you can open an account or pass identity checks, or whether you can deposit, place a bet or withdraw. It provides no tax clearance, income promise, loss-recovery method or assurance that an offsetting bet can be filled. Betting can lose money; understanding a calculation does not remove that risk.
Common questions
Is a 20-unit lay stake a 20-unit maximum loss?
Not if “stake” means the backer’s stake in this example. At decimal odds of 3.00, a matched 20-unit back stake gives the layer 40 units of liability before fees. Some interfaces instead display liability as their lay amount. Identify the field’s meaning and the applicable charges and settlement rules; the label alone is not a loss limit.
Is laying Team A the same as backing Team B?
Not in a market with a draw. Laying Team A to win takes the position that Team A will not win, which can include a draw as well as Team B winning. Backing Team B to win does not win on the draw. Other market definitions require their own outcome comparison.
Does an unmatched offer cancel an existing matched bet?
No. An unmatched opposing offer has not yet created an offsetting matched position. The existing matched bet remains exposed. A new match, cancellation request or apparent price is not a guaranteed exit, and any later match has its own price, charges and settlement terms.
Can I use the example’s 5% for any exchange?
No. The rate and positive-net-market-profit basis are fictional assumptions. Actual schedules can use different rates and bases, including charges on losing settled bets. First identify the account, market and applicable fee rules; multiplying an undefined “stake” by 5% does not reproduce this model.
Sources and limits
Definitions use Great Britain regulatory guidance. Betfair and Smarkets documents illustrate product-specific matching, liability, charges and settlement differences; their marketing claims are not adopted. References were checked on 18 October 2026. Examples use fictional monetary units and explicitly assumed full-settlement and commission rules. They exclude tax, rounding and other listed adjustments.
HypaForecast publishes educational guides and operates a prediction market. This guide explains betting mechanisms and fictional calculations; it does not recommend a service or transaction or determine whether any reader may participate.
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