The risk desk for event traders.
A read-only workbench for people who trade event contracts on more than one venue. It prices every edge after fees and states the error bound next to the number. It puts the settlement fine print side by side, because the wording decides whether you actually get paid. Your keys never leave your machine, and it places no orders. The free tier is launching shortly.
Get early access or just say hello at partnerships@splitrule.comBoth venues price fees on P(1−P), and most guides get the numbers wrong. Splitrule prices every edge after fees, from the published schedules, checked against live fills.
The top of the book may not hold your size. The screen reads the actual resting book and tells you whether your order clears at the price on your screen.
A 3¢ spread between venues reads as free money until both legs pay fees. Signed-in users see the after-fee basis in both crossing directions, carried with a worst-case bound.
Wording differences decide disputes, and disputes decide payouts. A side-by-side reading of each venue's rules text is in development. It is the reason this product exists.
And your keys stay yours. Read-only by construction, enforced in the type system. Credentials are sealed on your device and never transmitted. There are no Splitrule servers that could hold them.
FEE TRUTH · ISSUE 1
Most fee guides for prediction markets state numbers that match no primary source. These formulas come from the venues' own published schedules, read July 2026.
taker: fees = round up(M x 0.07 x C x P x (1-P)) M defaults to 1 maker: fees = round up(M x 0.0175 x C x P x (1-P)) M defaults to 0
At 50¢ the taker fee is 1.75¢ per contract. At 30¢ or 70¢ it drops to 1.47¢. Maker M defaulting to zero means you can place, cancel, and fill resting orders on most markets without paying a cent, and settlement is free. The current revision lists 86 non-standard series (each either maker-fees-on or entirely fee-free), and its volume-tiered tables apply to perpetual futures rather than event contracts.
taker: 0.06 x C x P x (1-P) 1.50¢ per contract at 50¢ maker: rebate of 0.0125 x C x P x (1-P)
The zero-fee era ended July 1, 2026. Many guides still miss this.
The example that kills naive arb. The same question trades on both venues. YES at 47¢ on one nets 50¢ on the other, a 3¢ gross edge. Free money, says the screen.
Take both legs and the fees add up. 1.74¢ on one venue plus 1.50¢ on the other is 3.24¢ against 3.00¢ of edge, a net of −0.24¢ per contract. The screen said profit. The schedules say loss. Splitrule exists to show you that verdict before you trade, computed correctly and bounded honestly.
Fees on both venues scale with P(1−P), peaking at 50¢ and falling toward the tails. Any flat per-contract fee quote is therefore wrong on both venues by construction. That is why Splitrule reads fee terms per market instead of assuming them.
Issue 2 will take up settlement wording, and how the same question can pay out differently depending on where you traded it. If you want it when it lands, the early-access note above covers you.