Prediction-Market Arbitrage Shrinks to 4%-5% as Bots and Fees Squeeze Retail Bettors
Updated
Updated · The New York Times · Jun 12
Prediction-Market Arbitrage Shrinks to 4%-5% as Bots and Fees Squeeze Retail Bettors
2 articles · Updated · The New York Times · Jun 12
Summary
Arbitrage on Kalshi and Polymarket now often yields just 4%-5%, down from about 8%, with openings lasting 2-5 seconds instead of roughly 30 seconds.
Bots run by Wall Street-style firms scan and execute trades across platforms faster than humans, quickly erasing price gaps that once let ordinary users lock in low-risk profits.
Fees are further eating into those thin edges: after Polymarket added charges in late March, one high-volume bettor said the change would have cost him more than $30,000 a month.
Some mismatches still appear — a March Gavin Newsom 2028 market offered roughly 3% profit for weeks — but long settlement times, rule differences and tied-up capital make many such trades less attractive.
The shift is pushing prediction markets toward the structure of other financial markets, where a tiny elite captures most gains; one-tenth of the top 1% of Polymarket accounts took more than two-thirds of profits.
As Wall Street bots conquer prediction markets, is the dream of easy money for individuals now dead?
With the first insider trading lawsuit, will prediction markets be forced to abandon their 'Wild West' ethos?
When algorithms trade in milliseconds, what is the ultimate purpose of a human-driven prediction market?
Prediction Market Arbitrage in 2026: How Bots, Institutions, and Regulation Squeezed Retail Profits
Overview
By June 2026, prediction market arbitrage has changed dramatically. The days when ordinary traders could easily find and profit from simple arbitrage are over. Now, the environment is dominated by sophisticated strategies, automated bots, and institutional players, making it much harder for individuals to compete. Arbitrage spreads on major platforms like Polymarket and Kalshi have tightened, and fleeting opportunities require fast, systematic, and risk-managed approaches. These changes mean that only those with advanced tools and strategies can consistently profit, while most retail traders face a shrinking pool of accessible gains in an increasingly complex market.