Being the House

Here is the mechanism, before its name. When ETH rises elsewhere, your pool's price is briefly stale, and the arbitrageurs from last checkpoint arrive to correct it. They buy your cheap ETH until the ratio matches the world. The rebalance happens through you.

Your booth ends up holding more of whatever fell and less of whatever rose. Travelers dump the falling currency; the booth dutifully buys it. That is what LPs quietly pay arbitrageurs whenever the world moves. Push the price yourself and watch the till.

Draw the business on the board. The dashed line is a person who simply held the two tokens. The solid curve is your LP stake. They touch on deposit day, and then any big move, in either direction, opens a gap between them.

The gap is not a fee, and nobody took it from a drawer. It is the rebalance you just ran, added up: the booth kept selling winners and buying losers, so the curve trails the line. Tap the three points to read it.

The gap you just read has a name, and the name arrives last because the name misleads. It is called impermanent loss. Impermanent: true only if the price walks all the way back to where you deposited. Nothing forces it to.

Loss lies too. It is a comparison against a person who simply held, not money missing from the till. Your stake can grow while the gap grows. You can be up, and still trail the holder.

Now the honest ledger of the business: LP profit equals fees earned minus that gap. Two columns, always both. A stable pair booth sees tiny moves: nearly no gap, and thin fees to match. A volatile pair swings hard: fat fees, fat gap.

There is no free lane; there is a price for every lane. Two friends are about to test you on exactly this.

One scenario deserves its own board. Stock a booth for a token that goes to zero, and the machine does exactly what you watched: it buys the falling token at every price, all the way down. Your USDC leaves; the dead token piles up.

The crowd selling it on the way down needed a buyer, and the buyer was you. The market has a polite name for that seat: exit liquidity. The house always trades. It does not always win.

Zoom out and pin the business to your map. The pot from last checkpoint gains an owner: the LP, paid in fees by traders, quietly rebalanced by arbitrage, carrying the gap against just holding. One booth, two columns.

One test before you close the till. A friend has heard about the gap and reached a conclusion. Find where their lens breaks.

You know the business now. The booth sells immediacy, traders pay the fee at the door, arbitrage rebalances the trays through you, and the gap against just holding is the cost that fee income must beat. Two columns, every pair, no free lane.

Then Uniswap v3 asked a strange question: what if the booth could choose where on the curve to stand? Next: concentrated liquidity, where LPing became a job.