Prisma

Learn how it works.

A tokenized stock is worth what the stock is worth, not what a pool was last pushed to. Everything below exists to keep the pool honest about that, and to refuse the trade when it cannot be.

What it is

Prisma Markets is a decentralised exchange for tokenized equities on Robinhood Chain. Each market is a pool holding a stock token and USDG, the chain’s dollar, and you trade against that pool rather than against another person.

What makes it different from an ordinary pool is that it is pinned: it knows what the share is actually worth, because a Chainlink price feed tells it, and it refuses any trade that would take it too far from that. A meme with the same ticker, a thin weekend, one aggressive buyer: none of them can move it.

The anchor

Every pool has a tolerance band around the oracle price, currently 1%. Trades inside the band go through normally. A trade that would push the pool further outside the band is rejected.

The check happens after the trade is calculated, not before, and that distinction matters. If a pool has drifted, the thing that repairs it is somebody arbitraging it back toward the oracle. So the rule is not “must end in band” but “must end in band, or closer to the oracle than it started”. Corrective trades are always allowed; only trades that make the gap worse are refused.

The band cannot be set tighter than 0.5%, because the feeds themselves only re-post when the price moves half a percent. A tighter band would be measuring the oracle’s own lag rather than any real drift.

Quoting

Liquidity Book will tell you how much a pool can absorb. That is a question about depth, and depth is not the only thing that can refuse a trade here. The anchor rejects on where the price ends up, which is a separate ground entirely, so a quote that knows only the first number is confidently wrong about every order large enough to reach the band.

The band is therefore quotable. One call answers how much of an order would actually fill, what it returns, and which of the two limits bit first. Another gives the largest trade the anchor will accept in a given direction right now, and a third reports the anchor’s own view of the pool. All three read the same functions the hook judges with, so a quote and a settlement cannot disagree.

The quoter is deliberately a little pessimistic. It rounds the room available down to whole bins and then gives one back. Being slightly conservative costs a trader a few cents of fill. Being slightly optimistic costs them a reverted transaction, and teaches them the venue cannot be trusted to know its own rules.

Resting orders

There is no order book here and nothing watching the market on your behalf. What there is instead falls out of how Liquidity Book already works: every bin is a price, and a bin on one side of the current price holds exactly one of the two tokens. Bins above hold the equity, bins below hold dollars.

So equity left in a bin above the price is an offer to sell there, and dollars left in a bin below it are a bid. When trading walks the price through that bin the contents convert, entirely, at the price the bin represents. Nobody has to be watching and no keeper has to act. The order is liquidity, and filling it is somebody else trading. Because it is liquidity, it earns fees the whole time it waits.

Two things follow that are not true of an order book. A filled order does not pay itself out: the proceeds sit in the position until you take them. And if the price comes back the other way it converts back, because a bin does not remember it was meant as an order. The fees are the compensation for both.