Guide
The one percent floor: set a minimum or do not sign
A swap with a minimum of zero will sell at whatever the pool offers, including a price that pays for someone else’s sandwich. One percent under the mark is the desk’s floor. Here is the arithmetic, and when to walk away instead.
MONAF Blog · 26 October 2026 · 15 min
amountOutMinimum is the only number in a swap that protects you from the pool moving between your signature and the block. Everything else is a wish. The desk sets it at 99 percent of the output it used to build the transaction. That output is the quote when a quote exists, and the slot0 mark when it does not. Zero is refused. A minimum that rounds to zero is refused. If the code cannot name a floor, it does not ask you to sign.
The arithmetic on a 50 MON clip
Suppose the card says the position would come back at 49.6812 MON. Ninety-nine percent is 49.1844 MON. The sell reverts rather than accept less. Your loss versus the mark, if you land on the floor, is about half a MON, one percent. The fee on the way in was already paid. You are choosing a bounded exit over a hopeful one. On the way in, the same rule applies to the tokens you expect. A 50 MON buy of WBTC that cannot name a token minimum is not sent.
One percent is wide enough for a single slot of ordinary noise on WETH and WBTC at this size, and tight enough that a sandwich which moves the pool by more than that fails your transaction instead of filling it. It is not wide enough for a thin pool. cbBTC’s round trip at 50 MON is nearer 0.8 percent before any adverse move. SOL on the Monad pool this desk watches is worse, and the desk does not offer it. If the round trip at your size is already over 1.25 percent, there is no trade, because the floor would have to sit inside the fee.
A minimum of zero is not a market order. It is a donation.
Size changes the fee
The same pool is a different product at 1 MON and at 50. WBTC’s round trip, measured from quotes rather than from a slogan, is about 0.35 percent at 50 MON and several percent at a 1 MON clip. The card prints that cost. If your target is 1.6 percent and the cost is 0.35, the target can pay the freight. If the cost is 7 percent, the target is a story you are funding. Read the cost line before the button. The floor will not save a trade that is expensive when nothing moves.
Two nodes, when you are entering
On the way in, when you still have a choice, two independent reads that disagree by more than two percent are a reason not to send. The minimum is built from the lower one. On the way out, when you have asked to leave, the desk does not go looking for a second opinion. The mark on the card is the opinion. Waiting for a second RPC is how Closing became a place people lived.
If the swap reverts on the floor
The pool moved through your percent, or the quote was stale, or the size was larger than the mark assumed. You still hold the position. Look at the new back amount. If you still want out, close again. The new floor is 99 percent of the new mark. Chasing by setting the minimum to zero will get you out and will also accept the worst price in the block. Do that only if you have decided, in writing to yourself, that any price is better than the position. The desk will not do it for you.