Trading on Lumina has two costs, both charged when your order executes: the ForecastEx transaction fee of $0.01 per contract and Lumina's commission of 0.35% of the trade value.

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) from ForecastEx as an exchange rebate. The rebate comes out of the $0.01 and isn't an additional charge to you.

Lumina charges a commission of 0.35% of the trade value each time you buy or sell, on top of the ForecastEx fee. The trade value is the contract price multiplied by the number of contracts, so the commission is never more than 0.35¢ per contract. Interactive Brokers, which carries your account, keeps a portion of it.

Both are charged at execution and aren't affected by how the contract resolves. Holding to settlement never adds a second charge; selling before resolution is a second execution, so it carries its own fee and commission.

A concrete example. You buy 100 Yes contracts at 60¢, a trade value of $60. The ForecastEx fee is $1.00 (100 contracts × $0.01) and Lumina's commission is $0.21 (0.35% × $60), so $1.21 in total. If the market resolves Yes, you receive $100 at settlement, having paid $60 for the contracts plus $1.21 in fees and commission, for a net profit of $38.79. If the market resolves No, you lose the $60.00 you paid plus the $1.21, or $61.21 in total.

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.