Tennis trading on prediction markets: the complete beginner's guide

Tennis trading on a prediction market means buying shares in a player at a price between 1¢ and 99¢, then selling them during the match or holding them to the end. Each share pays $1 if your player wins and nothing if they lose. The price is the market's guess at their chance of winning, and it moves with almost every point.

That's the whole idea. The rest of this guide explains how it works in practice, what it costs, where people go wrong, and how to practise without risking a cent. If a word is new to you, one of the linked guides probably explains it.

What a prediction market is

A prediction market is a place where people buy and sell shares in the outcome of an event. For a tennis match there are two outcomes: one player wins or the other does. Polymarket is the best known of these markets, and it lists a lot of ATP and WTA matches, including many smaller tournaments.

The important part is who sets the price. It isn't a bookmaker. It's other traders. Some want to buy, some want to sell, and the price is wherever they agree. When lots of people think a player is undervalued, they buy, and the price goes up.

How a tennis market works

Take a match between two players I'll call Player A and Player B. The market has two kinds of share, one for each player.

• If A wins, every A share pays $1 and every B share pays nothing.
• If B wins, it's the other way round.
• Before the end, you can sell your shares to someone else at the current price.

Because one of the two players has to win, the two prices add up to roughly $1. If A trades at 62¢, B will be close to 38¢. They rarely add up to exactly 100¢, and how tennis prices work explains why.

Each market also has written rules about what counts as a win. On Polymarket's tennis markets, the market pays out on the player who advances. That matters when a player retires injured, and I've covered those cases in what happens if a player retires mid-match.

What the price tells you

The price is a probability in disguise. A price of 62¢ means the market thinks A has about a 62% chance of winning. A share that pays $1 with a 62% chance is worth about 62¢ on average, so that's where the price settles.

So when you buy at 62¢, you're saying the real chance is higher than 62%. When you sell, you're saying it's lower, or that you're happy to take your profit now. You don't need a formula for this. You just need to ask: is this price too high, too low, or about right?

Buying and selling during a match

This is the part that makes it trading rather than a normal bet. You don't have to wait for the last point. You can sell at any moment while the market is open, at the going price.

That gives you a few ways a trade can end:

1. You sell early for a profit, because the price moved your way.
2. You sell early for a loss, because it moved against you and you want out.
3. You hold to the end, and each share pays $1 or nothing.

Notice the trade-off. Selling early limits both your upside and your downside. Holding to the end is all or nothing.

Why the price moves

Every point changes the odds a little, but some points change them a lot. These are the things that move tennis prices most:

• Breaks of serve. Most games are won by the server, so a break is a big deal. In a close men's match on a hard court, a break at 2-2 in the first set can move the leader from about 55¢ to about 69¢. Why the price jumps on a break of serve goes into this.
• Sets. Winning the first set of a best-of-three match is a huge step. In that same close match, the player who takes the first set goes from about 55¢ to around 78¢.
• Injuries and medical timeouts. A player calling the physio can knock 10¢ or more off their price in seconds.
• The surface. A break is worth more on grass, where serve dominates, than on clay. See how the surface changes tennis prices.

Is this just betting?

It's close, but not the same. With a normal bet you take a bookmaker's odds and you're locked in until the end, unless they offer you a cash out. On a prediction market you trade against other people, and you can get out whenever you like at the going price. The full comparison is in tennis trading vs tennis betting.

What doesn't change is the risk. You can still lose everything you put into a trade.

The costs people forget

The price you see isn't quite the price you get. Three things eat into your results on a real market:

• The spread. There's a best price to buy at and a slightly lower best price to sell at. On busy matches they're often 1¢ apart, and on quiet ones more. If you buy at 62¢ and sell straight away, you might only get 61¢.
• Fees. When I checked in October 2026, Polymarket's tennis markets charged a fee to takers, meaning orders that fill straight away against the order book. Orders that wait on the book to be filled didn't pay it. Fees change, so check Polymarket's own fee page before you trade. I go through the sums in Polymarket tennis fees explained.
• Minimum size and thin markets. The tennis markets I checked had a minimum order of 5 shares. On small tournaments there may not be many people trading, so a big order can move the price against you.

On the 77 Tennis demo I fill you at the displayed price, with no fee and no spread. That keeps practice simple, but it means real results would be a bit worse than your demo results.

The risks, honestly

I'd rather you read this part twice than skip it.

• You can lose all of your stake. If you hold and your player loses, the shares are worth nothing. You can't lose more than you paid, but you can lose all of it.
• Prices can jump past you. Tennis moves in steps. A break of serve can take a price from 60¢ to 45¢ between one look and the next, so you won't always get out where you planned.
• The market is usually about right. Thousands of people watch the same match. Beating the price over many trades is hard, and plenty of people who try lose money.
• It can feel like a game. Live tennis is fast and exciting, which makes it easy to trade too much. Set a budget before the match and stick to it.
• It isn't legal everywhere. Countries treat prediction markets differently. Check the rules where you live before you use real money.

A simple plan for your first trades

1. Pick one match. Choose one you can actually watch, or at least follow point by point.
2. Decide why you're buying. "I think 62¢ is too low because A has won their last three meetings on this surface" is a reason. "The price is going up" isn't.
3. Keep it small. With real money, only use what you're fine losing. On the demo, try trades of $20 to $50 so one bad call doesn't wipe you out.
4. Decide your exits before you enter. Where will you take profit, and where will you cut the loss? Take-profit and stop-loss for tennis trading shows how to set them.
5. Write it down. After the match, note what you expected and what happened. That's how you get better.

If you want a ready-made first strategy, trading the break of serve walks through one step by step.

How to practise without risking money

I built 77 Tennis for exactly this. You get $1,000 of demo money and a live board of tennis matches with real Polymarket prices, scores and charts. You can buy and sell during a match, set take-profit and stop-loss levels, and see how you rank on a weekly leaderboard that resets every Monday.

A couple of honest limits. The board refreshes about every 18 seconds, so it isn't tick by tick, and demo fills ignore fees and the spread. It's a practice tool, not a copy of the real thing. But it's a good way to learn how prices react to breaks, sets and injuries before you ever spend real money.

FAQ

Do I need to know a lot about tennis to trade it?

It helps, but you don't need to be an expert. You need to understand how scoring works, why breaks matter, and how form and the surface affect a player's chances. The market already prices in the obvious stuff, so knowing the basics well beats knowing lots of trivia.

Can I lose more than I put in?

No, not when you buy shares. The worst case is that your player loses and your shares pay nothing, so you lose what you paid. You can't owe more than that.

How much money do I need to start?

On the demo, nothing: you get $1,000 of demo money free. On Polymarket, the tennis markets I checked had a minimum order of 5 shares, so a few dollars is enough for a trade. Only ever use money you can afford to lose.

What happens if a player retires injured?

On Polymarket's tennis markets, if the match has started and one player retires, the market pays out on the player who advances. A walkover before the start usually pays 50¢ a share. Always read the rules on the market itself. There's more in this guide to retirements.

Can I trade before the match starts?

On Polymarket, yes. Markets usually open well before the first serve, and you can buy, sell or hold through the start. Prices tend to move slowly before the match, then with every point once it begins.