Buy both sides.
Keep the spread.
The same event often trades at different prices on Polymarket, Kalshi and Limitless. When YES on one venue plus NO on another costs less than $1, exactly one side pays $1 if both markets resolve the same way — the gap is yours.
See live spreads ↗
Polymarket
Kalshi$1,000 in → $1,041.67 back at resolution if both markets resolve the same way.
Method
Match
Every minute we pull hundreds of thousands of markets and pair up the same contract across venues — checking dates, thresholds, times and outcomes.
Price
For each pair we read live order-book asks, add each venue's taker fees, and price holding both YES and NO until resolution.
Profit
If the pair costs less than $1, you get ROI, APR and dollar profit for your budget, capped by the depth actually on the book.
The math
Cost of a pair = YES ask on venue A + NO ask on venue B + taker fees on both legs. If both markets resolve the same way, exactly one leg pays $1.
ROI / APR: ROI = ($1 − cost) ÷ cost. APR = ROI × 365 ÷ days until the later of the two markets resolves — that is how long your capital is locked.
Dollar profit = pairs × ($1 − cost), where pairs = budget ÷ cost, capped by the size available at the quoted asks on both books.
Fees: Kalshi charges about 0.07 × p × (1 − p) per contract; Polymarket applies each market’s published fee schedule (rates vary by category, some are zero).