The trading cost Lumina users incur is the ForecastEx exchange's transaction fee. A portion of that fee compensates Lumina; nothing is added on top of it.

ForecastEx charges $0.01 per contract, per side, at the time of execution. Both the Yes side and the No side of an executed transaction each pay $0.01.

Lumina receives 25% of that fee — $0.0025 per contract — as an exchange rebate. It isn't an additional charge. Your total cost is $0.01 per contract, per side, either way.

The fee is charged at execution and is not affected by how the contract resolves. Holding to settlement never adds a second fee; selling before resolution is a second execution, so it carries its own $0.01 per contract.

A concrete example. You buy 100 Yes contracts at 60¢. The transaction fee is $1.00 (100 contracts × $0.01). If the market resolves Yes, you receive $100 at settlement, having paid $60 for the contracts plus $1.00 in fees — a net profit of $39.00. If the market resolves No, you lose the $60.00 you paid plus the $1.00 fee.

Lumina charges no account maintenance fee, no inactivity fee, and no deposit fee.

Withdrawals can carry one. Your first two withdrawals each calendar month are free, whichever method you use; after that it's $1.00 for a linked bank account (ACH) and $10.00 for a wire. Those are charged by Interactive Brokers, which holds your funds — Lumina receives no part of them. Details in Withdrawing from your account.

Every fee that can be charged on a Lumina account is listed in the fee schedule.

Fees are one side of the arithmetic. Open positions also accrue an incentive coupon for as long as you hold them, whichever way the contract eventually resolves: Incentive coupons.