Guide

Polymarket copy trading: copying a whale without copying blindly

Every Polymarket trade is public, so you can see a big trader's bet and place the same one. That doesn't make it safe. A copy is a bet on one outcome: if it loses, what you paid is gone. Here's how to copy with your eyes open.

What copy trading is, and isn't

Copy trading means placing the same bet a trader you follow just placed. On Polymarket you can see a wallet's trades and open positions, so you know what they bought, at what price, and whether they still hold it.

It isn't arbitrage. An arbitrage spread pays the same whoever wins. A copy pays only if the outcome you copied wins. Whales lose too, and they can afford losses you can't.

Five checks before you copy

1. The price they paid vs the price now. If they bought at 40¢ and it's 46¢ now, you're paying more for the same bet, and the move they were betting on may already have happened.
2. Whether they still hold it. A whale who sold an hour later was trading the price, not betting on the result.
3. Whether it's really a bet. Big trades are often hedges, market making, or one leg of a trade on another venue. Check for an opposite position.
4. How expensive the outcome is. At 75¢ you risk three times what you can win. Long shots under 10¢ usually lose.
5. Your size. Copy with an amount you'd be fine losing, and decide in advance when you'd sell.

Plan your exit before you buy

The hard part of copying is the exit. Three common rules:

• Stop loss: sell if the position falls a set share of what you paid, such as 25%.
• Take profit: sell once it's up a set share. A copy bought at 40¢ that pays $1 can make at most 150%, so targets should stay realistic.
• Follow the whale out: sell when the wallet you copied sells most of its position. This works on Polymarket because wallets are public; Kalshi's trade tape is anonymous, so it can't be done there.

How copying works in ArbTrader

ArbTrader's whale tracker lets you copy a single whale trade by hand. Copying is never automatic: each copy is one limit buy that you size and confirm after seeing what you could lose. It refuses a copy once the price is 3¢ or more above what the whale paid, skips outcomes above 75¢ and long shots under 10¢, and lets you set a stop loss, a take profit, a daily limit, and (for Polymarket whales) an automatic sell when the whale sells.

Common questions

Is Polymarket copy trading profitable?

Sometimes, sometimes not. A copy is a bet on one outcome, and big traders lose bets too. Checking the price they paid, whether they still hold, and your own exit plan matters more than who the whale is. Not financial advice.

Can I automatically copy a Polymarket wallet?

ArbTrader doesn't copy wallets automatically. Each copy is one trade you size and confirm yourself. Automatic wallet-copying means taking every trade a stranger makes, including hedges and flips that aren't bets at all.

How do I know if a whale trade is a real bet?

Check whether the wallet still holds it, whether it also holds the opposite side, and whether it bought every outcome of the event. Flips, hedges and bundles aren't opinions on the result.

Can I copy Kalshi whales?

You can see big Kalshi trades on the trade tape, but it's anonymous, so you can't follow a specific trader or know when they sell.