Fees

GoMarket charges fees in two unrelated places: on CLOB trades, and on winning parlay payouts. The mechanics are different in each.

CLOB trading fees

Fees are charged on the taker asset — the asset flowing from taker to maker — and accrue to a per-mint fee vault PDA.

Fee vault   seeds = ["fee_vault", mint]

Maker’s side	Taker pays the maker	Fee taken in
BUY	outcome tokens	outcome tokens
SELL	collateral	collateral

The formula

price     = calculate_price(maker_amount, taker_amount, side);
min_price = min(price, ONE - price);

match side {
    Side::Buy  => (fee_rate_bps * min_price * outcome_tokens) / (price * BPS_DIVISOR),
    Side::Sell => (fee_rate_bps * outcome_tokens / BPS_DIVISOR) * min_price / ONE,
}

The min(price, 1 − price) term is the important part. It scales the fee by how far the price is from a certainty, so the effective rate is highest at $0.50 and falls toward zero at the extremes.

YES price	min_price	Relative fee
$0.50	0.50	maximum
$0.20 or $0.80	0.20	40% of max
$0.05 or $0.95	0.05	10% of max

A trader buying a 3¢ longshot is risking 3¢ to make 97¢. Charging them the same percentage as someone trading a coin flip would be a far larger share of their actual risk. Scaling by min(p, 1−p) keeps the fee proportional to the value at stake rather than to the notional.

Who pays

Takers pay; makers don’t. The validator enforces this at insert: an order that is marketable on arrival must carry at least the taker fee rate in feeRateBps, or it’s rejected. A resting order that is later taken doesn’t pay — it was the maker on that fill.

So feeRateBps on your order is not optional decoration. Set it correctly for the role your order will play, or the insert fails.

The on-chain handler independently validates fee <= taking, so a malformed fee rate cannot consume the entire payment.

Parlay fees

A parlay’s fee is charged on the gross potential payout, at claim time, and only on a winning slip.

fee = floor(potential_payout × fee_bps_at_create / 10_000)
fee = min(fee, potential_payout)
net = potential_payout − fee

Three properties:

• No fee on the stake. Placing a parlay costs exactly your stake.
• No fee on a loss. You lose the stake, nothing more.
• The rate is snapshotted at create time. fee_bps_at_create is written into the Parlay account when you place it and read back at claim. An admin update_config between those two moments cannot change what you pay.

The cap is 10% (fee_bps ≤ 1000), enforced at initialize and on every update_config.

At claim, the vault pays net to the user and fee to config.treasury in the same transaction.

Worked example

stake              $10
legs               3, at 50% / 40% / 25%
combined           0.05
potential_payout   $200
fee_bps_at_create  200  (2%)

fee = floor(200_000_000 × 200 / 10_000) = 4_000_000   →  $4
net = $200 − $4 = $196

Where fees go

Source	Destination
CLOB trade fees	Per-mint fee vault PDA, ["fee_vault", mint]
Parlay fees	config.treasury token account

Both are on-chain accounts controlled by the program’s admin authority, which in production is a Squads multisig.

Costs that aren’t fees

Cost	Notes
Solana transaction fees	Paid by the executor for CLOB settlement; paid by you for parlay instructions
Priority fees	The executor escalates these on retries
Mint / merge	No fee — a par conversion, not a trade
Redeem / refund	No protocol fee
Cancelling an order	Free; off-chain only
Spread	Not a fee, but usually your largest real cost on a thin book