Argentina vs Egypt: Kalshi followed Polymarket within seconds

Kalshi followed Polymarket within seconds on every price swing we found in the Argentina-Egypt World Cup match, including the two around the disputed VAR call and Argentina's stoppage-time winner. None of the gaps between the two books held for more than about a minute, and none of them were large. That is what an efficient pair of books looks like, not a trading opportunity.

On 7 July, Argentina beat Egypt 3-2 in a Round of 16 tie that Egypt's camp is still disputing. Egypt had all but won it. Yasser Ibrahim headed them ahead inside the first quarter of an hour, Messi had a penalty saved soon after, and by the hour mark Egypt were two goals up and defending a place in the quarter-finals. A Mostafa Ziko goal was ruled out along the way after a VAR check found a foul by Marwan Attia on Lisandro Martínez in the buildup, a foul the length of the pitch away from where the ball ended up in the net. Then the game turned. Cristian Romero headed one back from a Messi cross in the 79th minute, Messi levelled it himself in the 84th, and Enzo Fernández won it deep in stoppage time. A lead Egypt had held for an hour was gone in about fifteen minutes, and that disallowed goal became the moment Egypt's players kept returning to. Their head coach said afterward that "there are sometimes external factors that go beyond the technical aspects."

Polymarket's own numbers put $20.8 million through its "will Argentina win" market alone; Kalshi's open interest across the same three outcomes runs another $13.8 million behind it. We log both venues' ask price on that market roughly once a minute, and every time the two books disagree enough to clear a profit net of fees, our matcher logs the edge and the most anyone could have staked before running out of book depth. Against that much money moving through the market, here is everything we found.

Egypt's opening goal, in the 20th minute, opened the mildest gap. Argentina's price fell from 74% toward the high 40s, and for twenty-six seconds Polymarket's book alone was cheap enough across all three outcomes to clear $116 net of fees. Kalshi's book caught up inside a minute.

The sequence around Ziko's disallowed goal opened it twice more: $32 at minute 84, gone in fifty-five seconds, and $56 at minute 91, gone in eight.

The biggest dollar figure of the match, $122, came at minute 107 as Argentina leveled the score, against $1,082 of depth on the thin leg. Twenty seconds later the percentage read higher, 23% against 11%, but the depth behind it had fallen to $151, worth $34. Either way, both books were back in agreement inside a minute.

The widest percentage gap, 28% net of fees, came on Argentina's stoppage-time winner near minute 116. It was worth $12, because only $41 of depth was left on the thin side of the book by then.

Those are the notable swings. Across the full match our matcher logged sixteen of these moments, and net of fees they add up to $439, each open for anywhere from a few seconds to about a minute. Against $20.8 million in Polymarket volume or $13.8 million in Kalshi open interest on this exact market, $439 is a rounding error, not an opportunity. Each one is capped by whichever of the three outcomes had the least depth at that instant, and that thin leg ran from 25 contracts to about 3,660. The story here is speed, not money: Kalshi's book needed about one more sample, roughly a minute, to catch up to whatever Polymarket's book had already priced in, goal after goal.

A note on what is counted here. This is the confirmed-parity moneyline pair for the game, the one we are confident is pricing the same real-world outcome on both venues. Other markets on this same matchup, the total and the spread lines, sat in our review band that day and are held back from public numbers for the same reason described in how a mispricing closes: a stale quote or a mismatched pair can look like a gap that was never really there.

The moneyline pair carries one caveat of its own, which we disclose on the market. Kalshi states how it prices a cancelled game and Polymarket does not, so had the match been called off, the two books could have settled differently. It went the distance, so it never came up, but that unverified cancellation handling is why even a confidently matched pair like this rides in our manual-review lane rather than the automated arb feed.

The matched feed and the price history behind this chart are on REST, free to read on any plan. The Quickstart pulls your first feed on a free key.