What Is Dutching on a Betting Exchange?

Dutching on a betting exchange is a staking strategy where you place multiple back bets on different selections within the same market, adjusting the stake on each selection so that your profit (or loss) is identical regardless of which selection wins. Rather than backing a single outcome and accepting variable returns, dutching distributes your risk across multiple outcomes while maintaining a predetermined profit level.

The core principle of dutching is mathematical: if you have three horses in a race with different odds, you calculate the stake for each horse such that if any one of them wins, your return is exactly the same. This transforms uncertainty about which outcome will win into certainty about how much you'll profit if one of your chosen outcomes does win.

The Origin of the Term "Dutching"

The term "dutching" originates from the Prohibition Era in the United States, named after Arthur Simon Flegenheimer, known as the gangster Dutch Schultz. Schultz served as an accountant for Al Capone's criminal enterprise and reportedly developed this betting technique to manage bets on horse races. Rather than betting equal amounts on multiple horses, he calculated different stakes so that his profit would be identical regardless of which horse won. This gave him a mathematical edge and reduced his exposure to variance.

While some sources debate whether Schultz actually invented the technique, the name has persisted in betting circles for over a century. The strategy predates modern betting exchanges; it was originally used with traditional bookmakers, but the invention of betting exchanges like Betfair has made dutching far more practical and profitable because exchanges allow bettors to lay (bet against) outcomes in addition to backing them.

Dutching on Exchanges vs. Traditional Bookmakers

On a traditional bookmaker, dutching involves backing multiple selections at different bookmakers to achieve the same profit across outcomes. The advantage of exchanges is that they offer better odds (lower overround) and allow you to lay selections, which opens up additional dutching strategies like lay dutching (reverse dutching).

On a betting exchange, dutching typically involves:

• Back dutching: Backing multiple selections at exchange odds with calculated stakes
• Lay dutching: Laying multiple selections so the liability is equal across outcomes
• Commission consideration: Exchange commissions reduce your net profit, so the calculation must account for this

How Does Dutching on Exchange Actually Work?

The Mathematical Foundation of Dutching

The mathematics of dutching revolves around implied probability and stake distribution. Every set of odds contains an implied probability—the likelihood that the odds suggest an outcome will occur.

For decimal odds, the implied probability is calculated as:

Implied Probability = 1 / Decimal Odds

For example:

• Odds of 2.0 = 1 / 2.0 = 0.50 (50% implied probability)
• Odds of 5.0 = 1 / 5.0 = 0.20 (20% implied probability)
• Odds of 3.5 = 1 / 3.5 = 0.286 (28.6% implied probability)

Once you have the implied probabilities for all selections you want to dutch, you calculate the total of all implied probabilities. Then, for each selection, you divide its implied probability by the total and multiply by your total stake. This gives you the stake for each selection.

Formula: Stake on Selection = (Implied Probability of Selection / Sum of All Implied Probabilities) × Total Stake

The beauty of this formula is that it ensures equal profit across all selections, regardless of which one wins.

Step-by-Step Dutching Calculation Example

Scenario: Horse Racing

You've identified three horses in a race you want to back:

• Horse A: Odds of 4.5
• Horse B: Odds of 6.0
• Horse C: Odds of 8.0
• Total stake: £100

Step 1: Calculate implied probabilities

• Horse A: 1 / 4.5 = 0.2222 (22.22%)
• Horse B: 1 / 6.0 = 0.1667 (16.67%)
• Horse C: 1 / 8.0 = 0.1250 (12.50%)

Step 2: Sum the implied probabilities

• Total: 0.2222 + 0.1667 + 0.1250 = 0.5139 (51.39%)

Step 3: Calculate stake for each horse

• Horse A: (0.2222 / 0.5139) × £100 = £43.27
• Horse B: (0.1667 / 0.5139) × £100 = £32.45
• Horse C: (0.1250 / 0.5139) × £100 = £24.33
• Total staked: £100.05 (rounding difference of 5p)

Step 4: Verify the profit is equal

• If Horse A wins: £43.27 × 4.5 = £194.72 return; Profit = £194.72 - £100 = £94.72
• If Horse B wins: £32.45 × 6.0 = £194.70 return; Profit = £194.70 - £100 = £94.70
• If Horse C wins: £24.33 × 8.0 = £194.64 return; Profit = £194.64 - £100 = £94.64

Outcome: All three scenarios yield approximately £94.70 profit. If none of the three horses win, you lose your entire £100 stake.

The Role of Commission in Exchange Dutching

Commission is a critical factor in dutching on exchanges that many bettors overlook. When you place a back bet on a betting exchange and it wins, the exchange takes a commission on your net winnings. This reduces your actual profit below what the calculation suggests.

Betfair's standard commission structure (as of 2025) is approximately 5% on net winnings, though this varies by market type and membership tier. The Expert Fee system introduced in 2025 charges based on gross profit over a rolling 52-week period rather than per-bet commission.

How Commission Affects Dutching:

When you win a dutching bet, the exchange takes commission on your profit. This means your actual return is less than your calculated return.

Formula with Commission: Actual Profit = (Stake × Decimal Odds - Stake) × (1 - Commission Rate) = Net Winnings × (1 - Commission Rate)

Commission Impact Example:

Using the horse racing example above with a 5% commission:

• If Horse A wins: £194.72 - £100 = £94.72 gross profit
• Commission: £94.72 × 0.05 = £4.74
• Actual profit: £94.72 - £4.74 = £90.00 (approximately)

To account for commission in your original calculation, many bettors adjust their stake calculation to factor in the expected commission rate upfront. This ensures that your actual profit (after commission) is equal across all outcomes.

What Are the Differences Between Back Dutching and Lay Dutching?

Back Dutching on Exchanges

Back dutching is the traditional form of dutching where you place back bets (bets for something to happen) on multiple selections. You win if any of your backed selections wins; you lose if none of them win.

In the horse racing example above, backing three horses means:

• Win scenario: One of your three horses wins → You profit £90–£95
• Loss scenario: None of your three horses win → You lose £100

Back dutching is straightforward, intuitive, and the most common form of dutching on betting exchanges. It works well when you've identified multiple strong selections but aren't confident in any single one.

Lay Dutching on Exchanges (Reverse Dutching)

Lay dutching, also called reverse dutching, involves laying (betting against) multiple selections so that the liability is equal across all outcomes. You profit if any of your laid selections loses; you lose money if all of them win.

How Lay Dutching Works:

Instead of backing three horses to win, you lay three horses to lose. Your liability (the amount you could lose) is the same regardless of which horse wins.

Example:

• Lay Horse A at odds 4.5: Liability = £100 × (4.5 - 1) = £350
• Lay Horse B at odds 6.0: Liability = £100 × (6.0 - 1) = £500
• Lay Horse C at odds 8.0: Liability = £100 × (8.0 - 1) = £700

To equalize liability, you adjust your stakes:

• Lay Horse A £77.78 → Liability = £77.78 × 3.5 = £272.23
• Lay Horse B £58.33 → Liability = £58.33 × 5.0 = £291.65
• Lay Horse C £43.75 → Liability = £43.75 × 7.0 = £306.25

If any horse wins, your liability is approximately equal (around £280–£310). If all three horses lose, you keep your stakes: £77.78 + £58.33 + £43.75 = £179.86 profit.

Back Dutching vs. Lay Dutching Comparison

When to Use Each Approach

Use back dutching when:

• You've identified multiple selections you believe have good value
• You want to increase your chances of a winning bet
• You prefer limited, predictable losses
• You're trading in-play and want exposure to multiple outcomes

Use lay dutching when:

• You believe multiple favorites are overpriced
• You want to profit from one selection losing
• You can manage larger liabilities
• You're hedging existing back bets

How Is Dutching Different from Arbitrage Betting?

Dutching and arbitrage are often confused, but they are fundamentally different strategies with different mechanics, risks, and profitability profiles.

The Core Difference

Arbitrage betting involves backing one outcome at one bookmaker and laying the same outcome at a betting exchange, locking in a guaranteed profit regardless of the result. This is possible when the back odds at the bookmaker are higher than the lay odds at the exchange.

Example arbitrage:

• Back Team A to win at bookmaker at odds 3.0
• Lay Team A at exchange at odds 2.8
• Calculate stakes to guarantee profit

Dutching, by contrast, involves backing multiple outcomes at the same bookmaker or exchange, adjusting stakes so profit is equal across outcomes. You don't lock in a guaranteed profit; you only profit if one of your selected outcomes wins.

Commission and Profitability Comparison

Dutching avoids exchange commission if you place all bets with traditional bookmakers. However, if you use an exchange for back dutching, you'll pay 5% commission on winning bets.

Arbitrage requires using a betting exchange to lay, so you always pay exchange commission. This significantly reduces the profit margin. An arbitrage opportunity that looks like 5% profit before commission may only yield 1–2% profit after commission.

Example:

• Dutching with bookmakers: No commission on back bets → Full profit retained
• Dutching with exchange: 5% commission on winning bets → Profit reduced by 5%
• Arbitrage: Commission on exchange lay bets → Profit reduced by 5%+ → Often unprofitable

Risk Profile and Practical Considerations

Dutching risk:

• Selection risk: You lose money if none of your selections win
• Account restrictions: None — dutching is legitimate and sustainable
• Odds movement: Can affect your calculated equal profit
• Liquidity: May struggle to place large stakes on less popular markets

Arbitrage risk:

• No selection risk: Profit is guaranteed
• Account restrictions: High — bookmakers actively restrict and close accounts of arbitrage bettors
• Odds movement: Minimal impact due to quick execution
• Execution: Must place both bets quickly before odds move

Long-term viability: Dutching is sustainable long-term because it's a legitimate betting strategy. Arbitrage is difficult to sustain because bookmakers restrict accounts. Professional bettors typically use dutching as a core strategy and arbitrage opportunistically when odds align.

What Are the Advantages of Dutching on Exchange?

Increased Winning Frequency

The primary advantage of dutching is that it increases your chances of landing a winning bet. Instead of backing a single outcome, you're backing multiple outcomes simultaneously. This increases the probability that at least one of your selections will win.

Example: If you back three horses in a race, you win if any of the three wins. The probability of at least one of your selections winning is higher than the probability of a single selection winning, provided you've selected horses with reasonable odds.

This increased winning frequency can psychologically sustain you through betting periods and reduce the variance in your results. Rather than experiencing long losing streaks, you're more likely to have regular small wins.

Risk Management and Controlled Exposure

Dutching provides predictable, controlled risk. You know exactly how much you can lose (your total stake) and exactly how much you'll profit if one of your selections wins (your calculated profit). This makes bankroll management straightforward.

Contrast this with single-bet betting, where your loss is fixed (your stake) but your profit varies wildly depending on which outcome wins. With dutching, you control both your loss and your profit.

This is especially valuable for professional bettors who need to manage risk across a portfolio of bets. You can size your dutching stakes to ensure that even a losing day doesn't significantly impact your bankroll.

Flexibility in Market Selection

Dutching works on any betting market with multiple outcomes: horse racing, football (correct score, goals, corners), tennis, basketball, cricket, and more. You can adjust your approach based on the market you're betting on.

On some markets, you might dutch two selections; on others, you might dutch five or six. This flexibility allows you to adapt your strategy to market conditions and your confidence levels.

No Account Restrictions

Unlike arbitrage betting, dutching is a legitimate, recognized betting strategy. Neither bookmakers nor betting exchanges restrict or close accounts for dutching. This makes it a sustainable long-term approach, whereas arbitrage bettors often find their accounts restricted after consistent profits.

What Are the Disadvantages and Risks of Dutching on Exchange?

Lower Profit Margins

When you dutch multiple selections with similar odds, your profit margin per unit stake is lower than if you'd backed a single long-odds selection. This is because you're spreading your stake across multiple outcomes, and the profit is averaged across them.

Example:

• Single bet on 10.0 odds: £10 stake → £100 return → £90 profit (900% return)
• Dutching on three selections averaging 4.0 odds: £30 stake → £40 return → £10 profit (33% return)

While dutching increases your chances of winning, it reduces the size of each win. This is the trade-off: frequency vs. magnitude.

Commission Reduces Profitability

On betting exchanges, commission on winning bets directly reduces your profit. A 5% commission on every winning bet means your actual profit is 5% lower than your calculated profit. Over many bets, this compounds significantly.

Impact: On a £1,000 dutching bet that wins with a calculated profit of £100, a 5% commission costs you £5. This doesn't sound like much, but across dozens of dutching bets per month, commission can reduce your annual profits by 5–10%.

This is why many professional dutchers prefer using multiple bookmakers (to avoid exchange commission) rather than dutching on exchanges.

Odds Movement Risk

Odds change constantly on betting exchanges. If you place bets on multiple selections over a period of time rather than simultaneously, the odds may move between your first and last bet. This can disrupt your calculated equal profit.

Example: You calculate stakes for three horses assuming:

• Horse A: 4.5
• Horse B: 6.0
• Horse C: 8.0

By the time you place all three bets, Horse B's odds have shortened to 5.5 due to heavy betting. Your calculated profit is no longer equal across outcomes; Horse B now yields less profit than the others.

To mitigate this, professional dutchers place all bets as quickly as possible, ideally within seconds of each other.

Liquidity and Execution Issues

Not all betting markets have sufficient liquidity to accommodate large dutching bets. If you want to place £100 on each of three selections, you need £100 available at reasonable odds for each selection. On less popular markets, you may struggle to find the liquidity.

Additionally, if you're placing large stakes, the act of placing your bets may move the odds against you (slippage). This is especially true on less liquid markets.

Requires Accurate Calculation

Dutching calculations are straightforward in theory but error-prone in practice, especially when dutching three or more selections or accounting for commission. A small calculation error can result in unequal profits across outcomes, defeating the purpose of dutching.

While dutching calculators are available, they require you to input the correct odds and stakes. Manual calculation mistakes are common.

How Do You Calculate Dutching Stakes on an Exchange?

The Basic Dutching Formula

The core formula for dutching is:

Stake on Selection = (Implied Probability of Selection / Sum of All Implied Probabilities) × Total Stake

Breaking this down:

1. Implied Probability = 1 / Decimal Odds (for each selection)
2. Sum of Implied Probabilities = Total of all implied probabilities
3. Selection Stake = (IP / Sum) × Total Stake

Worked Example: Two-Way Dutching

Scenario: Football match, backing two teams to score.

• Team A to score: Odds 2.20
• Team B to score: Odds 2.50
• Total stake: £50

Calculation:

1. Implied probabilities:

   • Team A: 1 / 2.20 = 0.4545 (45.45%)
   • Team B: 1 / 2.50 = 0.4000 (40.00%)
   • Sum: 0.4545 + 0.4000 = 0.8545

2. Stakes:

   • Team A: (0.4545 / 0.8545) × £50 = £26.59
   • Team B: (0.4000 / 0.8545) × £50 = £23.41

3. Verification:

   • If Team A scores: £26.59 × 2.20 = £58.50 return; Profit = £58.50 - £50 = £8.50
   • If Team B scores: £23.41 × 2.50 = £58.53 return; Profit = £58.53 - £50 = £8.53

Result: Both outcomes yield approximately £8.50 profit.

Worked Example: Three-Way Dutching

Scenario: Correct score betting in football.

• 1-0: Odds 5.5
• 1-1: Odds 4.2
• 2-1: Odds 6.8
• Total stake: £100

Calculation:

1. Implied probabilities:

   • 1-0: 1 / 5.5 = 0.1818 (18.18%)
   • 1-1: 1 / 4.2 = 0.2381 (23.81%)
   • 2-1: 1 / 6.8 = 0.1471 (14.71%)
   • Sum: 0.1818 + 0.2381 + 0.1471 = 0.5670

2. Stakes:

   • 1-0: (0.1818 / 0.5670) × £100 = £32.07
   • 1-1: (0.2381 / 0.5670) × £100 = £42.00
   • 2-1: (0.1471 / 0.5670) × £100 = £25.93

3. Verification:

   • If 1-0: £32.07 × 5.5 = £176.39 return; Profit = £176.39 - £100 = £76.39
   • If 1-1: £42.00 × 4.2 = £176.40 return; Profit = £176.40 - £100 = £76.40
   • If 2-1: £25.93 × 6.8 = £176.34 return; Profit = £176.34 - £100 = £76.34

Result: All three outcomes yield approximately £76.35 profit.

Using Dutching Calculators

Rather than calculating stakes manually, most bettors use dutching calculators, which automate the process and reduce errors.

Popular dutching calculators include:

• Betfair Dutching Tool — Built into Betfair's platform; simple and reliable
• OddsMonkey Dutching Calculator — Designed for matched betting; includes commission adjustment
• BetAngel Dutching Calculator — Advanced tool with multiple dutching strategies
• SharpBetting Dutching Calculator — Free online calculator; supports up to 20 selections

How to use a dutching calculator:

1. Enter the decimal odds for each selection
2. Enter your total stake
3. (Optional) Enter the commission rate
4. Click "Calculate"
5. The calculator displays the stake for each selection and the expected profit

Calculators save time and eliminate human error, making them essential for dutching multiple selections or when commission adjustment is required.

When Should You Use Dutching on Exchange?

Ideal Market Conditions

Dutching is most effective when:

1. Multiple strong selections: You've identified 2–5 selections with reasonable odds (typically 2.5–10.0 range). If all your selections are long odds (10.0+), the total implied probability becomes very low, and your profit margins shrink.

2. Compressed odds: The odds on your selections are relatively close to each other. If one selection is 2.0 and another is 20.0, the stake distribution becomes very skewed, and you're essentially backing one selection heavily.

3. Uncertain outcome: The market outcome is genuinely uncertain, and you're not confident in a single selection. Dutching is a way to cover multiple possibilities.

4. High bookround: The market has a high overround (bookmakers' margin), creating inefficiency. Dutching can exploit this by covering multiple outcomes at favorable odds.

Sports and Markets Best Suited to Dutching

Horse racing: The classic dutching market. Multiple runners, varying odds, and sufficient liquidity make horse racing ideal for dutching.

Football:

• Correct score: Multiple possible scorelines with varying odds
• Goals (over/under): Two outcomes, but can be combined with other markets
• Corners: Multiple possible corner counts

Tennis: Multiple set outcomes or game outcomes; less suitable due to fewer possible outcomes.

Basketball: Multiple possible final scores or point spreads; high liquidity.

Cricket: Runs scored, wickets, match outcome; multiple possibilities.

General principle: Any market with 2+ distinct outcomes and reasonable odds is suitable for dutching. The more outcomes available, the more effective dutching becomes.

Bankroll and Stake Considerations

Minimum stake: You can dutch with any stake, but very small stakes (£1–£5) may not be worth the effort. Most bettors dutching on exchanges use stakes of £20–£100+ per dutching bet.

Bankroll sizing: Your dutching stakes should follow standard bankroll management principles. A common approach is to risk 1–2% of your bankroll per dutching bet. If your bankroll is £1,000, you might dutching £10–£20 per bet.

Risk of ruin: If you dutch frequently, even a small percentage of losses can accumulate. Ensure your stakes are small enough that a losing streak doesn't deplete your bankroll.

When NOT to Dutch

Avoid dutching when:

• One selection has significantly better odds than others (odds are heavily skewed)
• The market has low liquidity (difficulty placing large stakes)
• The potential profit is very small (less than 2–3% of your stake)
• You're highly confident in a single selection (dutching wastes stake on other outcomes)
• Odds are moving rapidly (difficult to execute all bets at calculated odds)

What Are Common Misconceptions About Dutching on Exchange?

Misconception 1: "Dutching Guarantees Profit"

Reality: Dutching does NOT guarantee profit. It only guarantees equal profit if one of your selected outcomes wins. If none of your selections win, you lose your entire stake.

Dutching is not a risk-free strategy. It reduces variance and increases winning frequency, but it doesn't eliminate risk. Your selection quality is critical. If you dutch poor selections with low implied probability of winning, you'll lose money consistently.

Misconception 2: "Dutching Is the Same as Arbitrage"

Reality: Dutching and arbitrage are fundamentally different strategies. Arbitrage backs one outcome and lays it simultaneously, guaranteeing profit. Dutching backs multiple outcomes, with profit contingent on one of them winning.

Arbitrage is risk-free but unsustainable (accounts get restricted). Dutching is selection-dependent but sustainable long-term.

Misconception 3: "Commission Doesn't Significantly Impact Dutching"

Reality: Commission substantially impacts dutching profitability, especially on tight odds. A 5% commission reduces your profit by 5% on every winning bet. Over 100 winning bets, you lose 5% of total winnings to commission.

Many dutchers switch from exchange dutching to bookmaker dutching specifically to avoid commission. If you're dutching on an exchange, always factor commission into your stake calculations.

Misconception 4: "You Can Dutch Every Market Successfully"

Reality: Some markets are unsuitable for dutching. Markets with very skewed odds, low liquidity, or poor odds availability make dutching ineffective or impossible.

A market where one selection is 1.5 and another is 20.0 is not a good dutching opportunity. You'd need to stake far more on the 1.5 selection, and your profit margin becomes minimal.

What Is the Future of Dutching on Betting Exchanges?

Evolving Commission Structures

Betfair introduced its Expert Fee system in 2025, replacing the traditional per-bet commission structure. Rather than charging 5% on every winning bet, the Expert Fee charges based on gross profit over a rolling 52-week period. This changes the economics of dutching.

Impact: Dutchers with consistent small profits may actually benefit from the Expert Fee, as their total commission could be lower. However, dutchers with high-volume, low-margin betting may face higher fees.

Other exchanges are likely to follow Betfair's lead, introducing new commission structures that incentivize different betting behaviors.

Automation and Advanced Tools

The future of dutching will likely involve more sophisticated automation:

• AI-driven stake calculators that adjust for market conditions in real-time
• Automated dutching bots that place bets across multiple outcomes simultaneously
• Real-time odds analysis that identifies optimal dutching opportunities
• Commission optimization that automatically selects the best exchange based on current commission rates

These tools will make dutching more accessible to casual bettors and more efficient for professionals.

Regulatory and Market Changes

The UK betting market continues to evolve with stricter regulations. Potential changes include:

• Affordability checks that limit stake sizes
• Betting limits that restrict dutching on certain markets
• Licensing requirements that affect exchange availability

Dutching is unlikely to be restricted, but regulatory changes may affect the profitability and mechanics of the strategy.

Frequently Asked Questions

Q: Can you dutch on place markets?

A: Yes, dutching works on place markets and each-way markets. The calculation is identical; you simply use the place odds instead of win odds. Place markets often have more favorable odds for dutching because the implied probabilities are higher (more horses can place than can win).

Q: What's the minimum number of selections you can dutch?

A: You can dutch on just two selections. Dutching becomes more effective with three or more selections because you increase your chances of a winner. However, two-way dutching is common and can be profitable if the odds are favorable.

Q: How does dutching differ from hedging?

A: Hedging involves placing a bet against your original bet to reduce potential loss or lock in profit. Dutching involves placing multiple bets upfront to equalize profit across outcomes. Hedging is reactive (you place a hedge after your original bet); dutching is proactive (you plan the multiple bets together).

Q: Can you dutch across different betting exchanges?

A: Yes, you can dutch across exchanges to find the best odds for each selection. However, you'll need accounts at multiple exchanges, and you must factor in commission from each exchange if applicable. The advantage is accessing the best odds; the disadvantage is managing multiple accounts and execution complexity.

Q: What happens if the odds change between placing your bets?

A: Odds movement is a real risk in dutching. If odds shift significantly after you've placed some bets but before you've placed others, your calculated equal profit may no longer be equal. This is why professional dutchers place all bets as quickly as possible, ideally within seconds. Some use betting apps that allow simultaneous placement of multiple bets.

Q: Is dutching on exchanges legal?

A: Yes, dutching is completely legal and legitimate. It's a recognized betting strategy used by professional bettors and is not prohibited by any major betting exchange or bookmaker. Unlike arbitrage betting, which some bookmakers frown upon, dutching is openly accepted.

Q: How does Betfair commission affect my dutching profit?

A: Betfair's commission (standard 5% on net winnings, or the Expert Fee system for eligible users) reduces your profit on winning bets. To account for this in your stake calculation, you can adjust the formula to:

Stake = (Implied Probability / Sum of Probabilities) × Total Stake × (1 - Commission Rate)

For example, with a 5% commission, multiply your calculated stake by 0.95. This ensures your actual profit (after commission) is equal across outcomes.

Q: Can you lay dutch on a betting exchange?

A: Yes, lay dutching (reverse dutching) involves laying multiple selections so the liability is equal across outcomes. This is less common than back dutching but can be profitable when you believe multiple favorites are overpriced. Lay dutching requires more careful bankroll management because your liability can be substantial.

Related Terms

• Dutching — The general dutching concept
• Lay bet — Betting against an outcome on an exchange
• Betting exchange — How exchanges work
• Back bet — Betting for an outcome
• Matched betting — Related strategy combining back and lay bets
• Arbitrage betting — Risk-free betting strategy
• Commission — Exchange fees on winnings
• Implied probability — Key calculation concept