// GLOSSARY

Best execution

The obligation (or discipline) of executing orders on the terms most favorable to the order's owner — best net price after fees, across available venues. In prediction markets it means comparing Kalshi and Polymarket fee-adjusted, not just quoted prices.

In regulated securities markets, best execution is a formal duty brokers owe clients. In prediction markets nobody owes it to you — which is exactly why it's worth enforcing on yourself: the same contract often trades on both Kalshi and Polymarket at different net prices.

What "best" means

Not the best quoted price — the best fee-adjusted net price for your size. A 43¢ Kalshi ask can be worse than a 0.44 Polymarket ask once Kalshi's taker fee is added, and the ranking can flip with size as fees and book depth interact.

Proving it

The honest standard is evidence per fill: what both venues showed at order time, what you paid, and the delta. That's the role of the execution receipt — Mithril attaches one to every fill so the savings claim is your number, not a marketing average. The full argument is in execution receipts and best execution.