Why Cross-Chain Market Makers Price From Inventory

Cross-chain market makers price a swap partly by asking what assets they will hold after it fills. A trader sends one asset on a source chain and expects another on a destination chain. The market maker must have access to the asset owed, or a way to obtain it, and must account for how the trade changes the assets left in its inventory.

The steps are straightforward. First, the trader’s deposit is confirmed and the swap details identify the destination asset and address. Next, a market maker offers liquidity at a price. When the swap executes, the market maker receives the deposit asset and supplies the output asset. It can then keep, trade or hedge what it received, and replenish what it paid out.

That last step shapes the quote. If a maker already holds plenty of the output asset, selling more may be less attractive; if the trade brings in an asset it wants, it may accept a tighter spread. The same logic applies to an inventory it can hedge elsewhere. For the protocol-specific path from deposit to native-asset payout, see chainflip. The details vary by system, but inventory is the link between a trade’s stated rate and the maker’s cost of fulfilling it.

How does inventory change a swap price?

Inventory changes a quote because each filled trade moves the maker’s balances in a particular direction. A swap from asset A to asset B gives the maker A and uses up B. The maker weighs the trade’s price against the value and availability of both assets after settlement.

Consider a market maker with limited B. A trade that pays out a large amount of B leaves less available for the next swap. The maker may quote a worse rate, reduce the size it is willing to fill, or seek B elsewhere. If the maker has ample B and wants more A, it may offer a more competitive rate. These adjustments help price the cost of inventory risk and rebalancing, alongside fees and market movement.

For a cross-chain trade, replenishing inventory can involve extra steps. The maker may hedge on another venue, move funds between markets, or wait for further user flow in the opposite direction. Each option has a cost or delay. A quote can therefore reflect not only the current market price, but also how practical it is to restore the maker’s position.

What happens to inventory during a cross-chain swap?

In a cross-chain swap, the protocol tracks the trade across its settlement process while the market maker manages the assets used to fill it. The user’s deposit is confirmed on the source chain; swap instructions identify the output; then liquidity fills the swap and the protocol arranges the destination-chain payout. The market maker’s balance changes when it provides the output and receives the input.

Some systems use an automated market maker with standing liquidity. Others let market makers submit or update orders around incoming swaps. In Chainflip’s documented JIT AMM, liquidity providers monitor deposits, submit orders, and swaps are bundled and processed at the end of a block. A filled order returns the swapped assets to the provider’s balance, which can then be used for another trade or rebalancing.

The market maker’s inventory is not the same thing as the protocol’s full custody or settlement machinery. Validators, vaults and accounting rules may handle deposits and payouts, while the maker decides how much liquidity to offer and at what price. That separation lets a maker use external markets or its own holdings to manage exposure, depending on its strategy and access.

What should a trader compare in a quote?

A quoted output amount reflects more than a headline exchange rate. Compare the amount you will receive after the trade’s fees and any price impact, and check how long the quote remains usable. A large swap can consume more of the available inventory and receive a different effective price than a small one.

• Output amount: Compare the destination asset amount after listed fees.
• Trade size: Check whether the quote changes as the requested amount grows.
• Execution terms: Look for the expiry, confirmation conditions and any minimum output protection.
• Route: If the swap passes through an intermediate asset or pool, each step can affect the final amount.

Inventory-based pricing makes the market maker’s constraints visible in the rate: scarce output, costly hedging or a difficult rebalance can widen the price. For most traders, the better choice is the route with a clear final output and execution terms that fit the trade, rather than a comparison based on the nominal rate alone.