Guide

How to use ArbTrader, step by step

No experience needed. This guide starts from zero: what a prediction market is, why some trades pay no matter who wins, how to set everything up, how to place your first one, and how to split your money. Take it one part at a time.

Part 1: The big idea

What is a prediction market?

A prediction market is a website where you can buy a “yes” or “no” on a question, like “Will the Lakers win tonight?” Two of the biggest are Kalshi and Polymarket (and Polymarket US for people in the United States).

Each share is called a contract. When the question is decided:

• If you’re right, your contract pays $1.
• If you’re wrong, it pays $0.

Prices are in cents. If “Lakers win: Yes” costs 45¢, people think there’s roughly a 45% chance it happens. You pay 45¢ and get $1 back if the Lakers win.

Why two websites can disagree

Kalshi and Polymarket are different websites with different people trading on them, so the same question can have slightly different prices on each. Sometimes the difference is big enough to make money no matter who wins. That’s called arbitrage, and the trade is called a spread.

A simple example

Each thing you buy (the Kalshi contract and the Polymarket contract) is called a leg. Together the legs make one set. Some spreads have 2 legs, some have more (for example, one for every candidate in an election, where exactly one will win).

The catch (read this)

• Spreads are rare and fast. Most close within minutes as other traders notice them. That’s why ArbTrader scans all the time and pings you.
• You have to buy every leg. If you buy the Kalshi leg but the Polymarket price changes before you buy the other leg, you’re just holding a normal bet that can lose. ArbTrader’s order ticket helps prevent this (Part 4).
• Your money waits. You get paid when the question is decided. For a game that’s tonight; for an election it could be months.
• The rules must match. Both websites must be asking exactly the same question, decided the same way. ArbTrader checks this, and the AI Analyst can double-check any market.

Part 2: Get set up

Rather do this with someone? The ArbTrader team helps one to one in our Discord: setup, keys and your first spread.

Step 1: Make your ArbTrader account

Sign up at arbtrader.co. The free plan shows every spread as it appears. The Quant plan adds the exact legs and prices, how much you can buy, alerts, and one-tap order tickets. Quant is $1.48 a day, starting with your first 7 days.

Step 2: Check that you’re allowed to trade

Kalshi, Polymarket and Polymarket US each have their own rules about age and where you live. Open the State Guide on your dashboard to see which ones you can use. Only use websites you’re allowed to use.

Step 3: Open accounts on the trading websites and add money

ArbTrader finds the trades. You place them on Kalshi and Polymarket (or Polymarket US), so you need an account with money on each. Not sure how much? Part 7 has examples. Many people start with $100–$500 while they learn.

Step 4: Turn on alerts (most important step)

Good spreads last minutes, not days. If you only check the website now and then, you’ll mostly see them after they’re gone.

1. Open your dashboard and go to the Alerts tab.
2. Turn on notifications for your phone and computer. On iPhone, first add ArbTrader to your Home Screen (Share → Add to Home Screen), open it from there, then turn notifications on.
3. If you use Discord, connect it. The ArbTrader bot will DM you the moment a spread appears.
4. Set your minimums. A good start: at least 1% return and at least $1 profit.

Step 5 (optional): Connect your trading accounts

On the Connections tab you can add a Kalshi or Polymarket US API key. Then you can place both legs from ArbTrader in one tap and see your profit and loss. Your keys stay in your own browser; they’re never sent to us. The connection help page walks you through it.

Part 3: Read a spread

Every spread on the dashboard shows the same few things. Here’s what each one means:

Quick check: profit you’ll actually make = return × how much you put in. A 5% spread with only $12 available makes about 60¢. A 2% spread with $200 available can make $4.

Part 4: Place your first spread

Start small. The goal of your first trade is to learn how it works, not to make money. About $10 is plenty.

1. Wait for a ping. When an alert arrives, tap it. It opens that spread with live prices.
2. Check when it pays. For your first one, pick something that pays within a day or two so you can see the whole thing finish.
3. Check the legs. Make sure you can trade on every website listed. If a leg is on a website you can’t use, skip it.
4. Open the order ticket. On the dashboard’s Get started list, “Take your first spread with about $10” picks the best spread you can place and fills in about $10 for you. Or tap the Place button on any spread.
5. Read the ticket. It re-checks every price right now and shows what it will cost. If the spread just closed, it tells you, and you simply skip it.
6. Tap Place orders. ArbTrader buys the leg with the least available first. Orders are fill-or-kill: each one either buys the full amount at your price or buys nothing. So if the first leg can’t be bought, nothing else is sent and you’re not stuck.
7. Check the result. “Every leg filled” means you’re done: the spread will pay out on its own. You don’t need to sell anything.

Placing by hand works too: open each website from the links on the spread and buy each leg yourself. Buy the leg with the least available first, and do it quickly.

Part 5: After you’re in

• Positions tab: shows each spread you hold, what it would sell for right now, and what it pays at the end.
• Waiting: when the question is decided, the website pays the winning leg automatically. Your $1 per set shows up in that account.
• Exit early (optional): sometimes you can sell both legs before the end and keep most of the profit, for example 80% or more. That frees your money days or weeks sooner for the next spread. The “Exit early” button sets this up, and we’ll email you when it’s ready if the page is closed.
• Interest: Kalshi currently pays interest on money in your account and in open trades (3.50% a year, can change; US accounts with an average balance of $250 or more). It’s small, but it adds up while you wait.

Part 6: Pick the best spreads

The most important idea: fastest money

Money that’s waiting can’t be used for the next spread. So a smaller return that pays quickly often beats a bigger return that pays slowly.

Our own numbers show how much this matters. We took every spread the dashboard listed from September 30 to October 26, 2026, and pretended to trade them with $1,000. Taking only spreads that paid at least 1% per day of waiting ended about 2.3 times higher than taking every spread in the order it appeared (+$382 vs. +$168). That’s a pretend test, not real trades, but the lesson is clear.

When fast spreads show up

Many fast spreads are sports games (NBA, NHL, college football, and college basketball from November) where Kalshi and Polymarket disagree on who will win. They show up in the hours around game time and pay out the same night. Afternoons are usually quieter. This is why alerts matter so much.

Skip these

• Tiny ones: under about $20 available. The profit is too small to bother.
• Slow and small: 1% that pays in 3 months is only about 4% a year.
• Too good to be true: a live game showing 15% usually means a price that’s out of date and won’t actually fill. ArbTrader hides most of these, but stay skeptical.
• Unclear rules: if two websites’ questions aren’t clearly the same, open the AI Analyst and check that both decide the same thing, at the same time, the same way.

Part 7: Split your money

These are simple rules of thumb to start with, not advice for your situation. Try them for a few weeks and adjust.

Walk-through: starting with $500

1. Put about $330 on Polymarket and $170 on Kalshi.
2. Your limit per spread is $50 (10%).
3. Keep at least $125 unused at any time (25%).
4. At most $150 in spreads that pay out more than a month away (30%).
5. When an alert comes in, check: Does it fit under $50? Do I have the money on both websites? Does it pay soon? If yes, place it.

Example setups

• $500: great for learning. Many spreads only have $20–$80 available anyway, so a small amount gets used well.
• $2,000: enough to be in several spreads at once and still have money ready at game time.
• $10,000: more money doesn’t mean the same percent. Most spreads don’t have $1,000 for sale, so you’ll often be limited by what’s available. Expect more dollars but a lower percent.

Want to see what this would have done? The with vs. without ArbTrader chart on the homepage runs it with real listed spreads for $1,000, $5,000 and $10,000. It’s a pretend test that assumes every leg was bought at the listed price, so real results are lower.

Mistakes to avoid

• Thinking half a spread is safe. One leg by itself is a regular bet.
• Putting most of your money in one big, slow spread because the percent looks high.
• Keeping all your money on one website, then missing every spread that needs both.
• Reading only the titles. “Above 92” and “at least 92” sound the same, but at exactly 92 one says yes and the other says no.
• Waiting too long. If you think about it for ten minutes, it’s usually gone.

Words to know

Common questions

How much do I need to start?

You can learn with $100–$500. Many spreads only have a small amount available, so starting small isn’t a problem.

Is this risk-free?

A complete spread pays a fixed amount no matter who wins. But getting there has real risks: a leg might not fill, prices can change while you buy, two websites can decide a question differently, and your money is stuck until it pays out. Read Risks before you start.

Should I wait for the result or exit early?

Waiting gets you the full profit. Exiting early is worth it when you can keep most of the profit now and the payout is still days or weeks away, because that money can go into the next spread.

Do I need to watch the screen all day?

No. Turn on alerts and go about your day. When your phone pings, take a look.

This guide is for learning, not financial advice. Prediction markets involve risk, including losing money you put in. Past and pretend (hypothetical) results don’t predict future results. Only trade on websites you’re allowed to use where you live.