# Dutch-auction swap orders: a price that changes until someone fills

A Dutch-auction swap order changes its acceptable exchange amounts over time until a filler finds execution worthwhile. The documented UniswapX example starts with a higher requested output and decays toward a minimum. A later fill can satisfy the signed order while producing less output than the initial auction amount.

Evidence: [UniswapX Overview](https://docs.uniswap.org/contracts/uniswapx/overview)

Canonical: https://degreesofsatoshi.com/encyclopedia/dutch-auction-swap-orders/
Published: 2026-10-02
Substantively modified: 2026-10-02
Independently verified by an automated reviewer: 2026-10-02T19:18:00.092Z
Data current through: 2026-10-02

AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied.

## Key facts

- **Curve:** UniswapX’s Dutch-auction example defines output amounts over time. ([UniswapX Overview](https://docs.uniswap.org/contracts/uniswapx/overview))
- **Executor:** Fillers compete to settle an economically viable order. ([UniswapX Overview](https://docs.uniswap.org/contracts/uniswapx/overview))
- **Scope:** UniswapX uses different auction mechanisms on different supported chains. ([UniswapX Overview](https://docs.uniswap.org/contracts/uniswapx/overview))

## Evaluate the price at the fill time

Suppose a hypothetical order sells 100 A, initially requesting 102 B, with a linear decay to 99 B over 30 seconds. At 20 seconds, that curve requests 100 B. A fill at 100 B is consistent with the illustrative curve even though it is below the initial 102 B.

This is a teaching example, not a current UniswapX duration, parameter recommendation or claim that every auction uses linear decay.

Evidence: [UniswapX Overview](https://docs.uniswap.org/contracts/uniswapx/overview)

## A filler compares the obligation with execution cost

The filler needs to deliver the required output while obtaining the input, paying execution costs and handling its own trading strategy. Competition can encourage earlier execution, but a market move or lack of interest can leave an order unfilled.

The minimum and validity conditions are more useful protections than an expectation that someone will take the initial price.

Evidence: [UniswapX Overview](https://docs.uniswap.org/contracts/uniswapx/overview)

## Do not generalize across auction types

The retrieved overview explicitly describes chain-specific mechanisms. Identify the concrete order format before interpreting a curve. Record actual fill amounts and time when comparing outcomes; an initial auction amount is not the same kind of quote as a guaranteed exchange.

Evidence: [UniswapX Overview](https://docs.uniswap.org/contracts/uniswapx/overview)

## Questions

### Does a decaying output mean I can lose more than the signed limit allows?

A correctly enforced order must remain within its authorized conditions. The limit is the relevant bound; the initial auction amount is not a guaranteed result.

Evidence: [UniswapX Overview](https://docs.uniswap.org/contracts/uniswapx/overview)

## Claims and scope

### dutch-auction-swap-orders-quick-answer

A Dutch-auction swap order changes its acceptable exchange amounts over time until a filler finds execution worthwhile. The documented UniswapX example starts with a higher requested output and decays toward a minimum. A later fill can satisfy the signed order while producing less output than the initial auction amount.

Scope: {"collection":"defi","dataAsOf":"2026-10-02","blockHeight":null}

### dutch-auction-swap-orders-fact-curve

Curve: UniswapX’s Dutch-auction example defines output amounts over time.

Scope: {"collection":"defi","dataAsOf":"2026-10-02","blockHeight":null}

### dutch-auction-swap-orders-fact-executor

Executor: Fillers compete to settle an economically viable order.

Scope: {"collection":"defi","dataAsOf":"2026-10-02","blockHeight":null}

### dutch-auction-swap-orders-fact-scope

Scope: UniswapX uses different auction mechanisms on different supported chains.

Scope: {"collection":"defi","dataAsOf":"2026-10-02","blockHeight":null}

## Sources

- [UniswapX Overview](https://docs.uniswap.org/contracts/uniswapx/overview) — Uniswap. Outcome-based swap authorization and filler settlement. Locator: Signed orders; fillers; auctions. Retrieved: 2026-10-02T18:53:19.990Z.

## Revision history

- 2026-10-02: First publication after primary-source research and separate automated verification.

## Cite this entry

Degrees of Satoshi editorial project. “Dutch-auction swap orders: a price that changes until someone fills.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/dutch-auction-swap-orders/