Last Tuesday I bought Yes on a Fed rate decision contract at 47 cents and, three seconds later, bought No on the same contract at 51 cents. That's 98 cents total for a guaranteed dollar payout. Two cents of locked-in profit, no directional risk. The fills happened because someone on the other side fat-fingered an order. I'll take it.
Every binary contract on Kalshi has two sides: Yes and No. By definition, exactly one of them settles at $1.00 and the other at $0.00. If you can buy both sides for less than a dollar combined, you pocket the difference when the contract resolves. Simple math, but the execution is where things get interesting.
This arbitrage exists because Kalshi runs a central limit order book, not an automated market maker. That means prices are set by other traders placing bids and offers. When liquidity is thin or someone makes a mistake, the Yes ask plus the No ask can briefly dip below $1.00. Your job is to spot that gap and hit both sides before it closes.
A few conditions that create these windows:
You can't watch every market manually. Kalshi lists hundreds of contracts across Fed decisions, inflation prints, weather events, and political outcomes. I keep a watchlist of maybe 20 to 30 active markets and check the order books a few times a day. When I worked the CME desk, we had screens that calculated implied probabilities across related products. Here, you're mostly doing it by hand or writing your own scripts if you're comfortable with the Kalshi API.
The basic screen is dead simple: pull the best ask on Yes, pull the best ask on No, add them together. If the sum is less than $1.00, you have a theoretical arb. If it's less than $0.98 or so, you might have something worth trading after fees.
Kalshi charges fees on trades (currently a few cents per contract, depending on the market). You also pay fees when the contract settles. So that two-cent arb I mentioned earlier? After fees, it was closer to a penny. Still free money, but you need to do the math before you click.
Slippage is the bigger killer. If you buy Yes and then the No side gets lifted before you can execute, you're stuck holding a directional position you didn't want. Speed matters. I usually have both order entry windows open side by side so I can fire both legs within a second or two.
Here's my workflow when I spot a potential arb:
Most of these opportunities last seconds, not minutes. If you're thinking about it, someone else is already trading it. The edge goes to whoever is watching at the right time and can act fast.
Here's where I've gotten burned. You buy Yes at 52 cents, planning to buy No at 46 cents for a clean arb. But by the time you switch screens, the No ask has moved to 50 cents. Now you're in at $1.02 total, which means you're underwater no matter what happens. You've turned a risk-free trade into a guaranteed loser.
Your options at that point are bad:
I've done all three. The cleanest answer is to be disciplined about leg risk. If you can't get both sides filled within your target window, walk away. There will be another opportunity.
Pure Yes/No arbs are rare because other traders are watching for them too. A more common situation is finding contracts where the implied probabilities don't add up across related markets. For example, if Kalshi lists separate contracts for "Fed holds rates in June" and "Fed cuts rates in June" and "Fed hikes rates in June," those three outcomes should sum to roughly 100%. When they don't, you might have a trade.
I share setups like this in the Telegram channel I run when I spot something interesting. No promises, and I'm often wrong. But talking through the logic with other traders helps me pressure-test ideas before I put money down.
These aren't pure arbitrage plays. They involve some judgment about how the market will re-price as more information comes in. But they're grounded in the same basic insight: binary outcomes have mathematical constraints, and markets sometimes violate those constraints.
I want to be honest about the ceiling here. Pure Yes/No arbs on Kalshi are not going to make you rich. The opportunities are small, infrequent, and heavily competed. If you're looking for top Kalshi strategies that scale, you probably need to take directional views on outcomes you actually know something about.
What arb hunting does give you is a way to stay engaged with the order books, learn how prices move, and occasionally pick up a few bucks when someone else makes a mistake. It's a good training ground. It teaches you to think about prices in probability terms and to respect the bid-ask spread.
For a regulated, CFTC-supervised exchange like Kalshi, where everything is KYC'd and settled in USD, having any mechanical edge is valuable. You're not going to find the same mispricings you'd see on offshore books with thinner oversight. But they do happen.
Not often. I might see a clean arb once or twice a week across the markets I watch, and many of them close before I can act. The best opportunities tend to appear during news events or in low-liquidity contracts. You need to be patient and ready to move fast when something shows up. Most days, there's nothing actionable.
Not strictly. You can scan order books manually on the Kalshi website. But if you want to monitor dozens of markets efficiently, writing a simple script against the Kalshi API helps. I use a basic Python setup that pings prices every few seconds. Nothing fancy, just enough to alert me when the Yes and No asks sum to less than a dollar.
There's no hard minimum, but the opportunities are small in absolute terms. If you're making two cents per contract on a 50-contract arb, that's a dollar before fees. You need enough capital to trade meaningful size, and you need to accept that the percentage returns are modest. I treat it as a supplement to directional trading, not a primary income source.
Yes. If you only get one leg filled and the other side moves against you, you're stuck with a directional position at a bad price. You can also miscalculate fees or get hit by settlement costs you didn't account for. Pure arbitrage is only "risk-free" if you execute both sides at the prices you planned. Partial fills and execution errors turn it into speculation.
Not financial advice. I trade my own money and you can lose yours. Do your own research.