Uniswap partners with Spark to launch the open-source DualPool Hook: put idle market-making funds into a vault to earn yield, with fees and returns benefiting both.

Uniswap Labs and lending protocol Spark have officially launched the open-source Hook “DualPool” they jointly developed. It allows market makers to deposit funds into an ERC-4626 yield vault to earn interest during idle periods before a trade is executed; once someone places an order and the price reaches the specified range, the hook pulls the needed concentrated liquidity back into the pool for matching within the same transaction, enabling market makers to earn both trading fees and vault yield.
（Background: Spark teamed up with Uniswap to launch stablecoin exchange infrastructure “FX Layer,” with the first wave supporting USDS, USDT, and PYUSD）
（Additional background: MakerDAO launched the lending protocol “Spark,” providing fixed-rate borrowing centered on DAI and ETH）

Table of contents

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• Idle money can also earn yield
• Stablecoin exchange is the main battleground
• After open-sourcing, anyone can deploy

Key takeaways

• The open-source Hook “DualPool” jointly developed by Uniswap Labs and Spark completed audits in July and is now live; any team can deploy it
• DualPool allows market-making idle funds to be deposited into an ERC-4626 yield vault to earn interest; when trading hits the price range, liquidity is pulled back to execute matching, letting LPs earn both trading fees and vault yield
• Spark has migrated $150 million in stablecoins (USDS, USDT, PYUSD) to Uniswap v4, generating about $1.5 billion in trading volume over 30 days

The biggest headache for market makers is that they put capital into a liquidity pool waiting for trades, but for most of the time, no one actually trades—so the money just sits there doing nothing. The open-source Hook “DualPool” officially launched by Uniswap Labs and the lending protocol Spark is designed to solve exactly this old problem. According to Uniswap’s official explanation, DualPool lets a market maker’s idle funds first go into a yield vault to earn interest, and only when a real trade comes in does it immediately pull the required liquidity back into the pool for matching.

For the issue of idle capital, DeFi has talked about it for years. DualPool’s solution isn’t to try to eliminate it—it simply acknowledges it can’t be avoided, and turns idleness into earnings.

Idle money can also earn yield

The operating logic isn’t hard to understand. A market maker’s capital is usually placed in Spark’s ERC-4626 yield vault (a standardized yield vault) to earn interest. Only when the price of a trade falls into the market maker’s configured range does DualPool, within the same transaction, extract just enough concentrated liquidity from the vault to complete the match; then, within the same block, it returns the remaining funds to the vault to keep earning interest.

That means liquidity providers (LPs) benefit in two ways: they collect trading fees and also the vault’s interest yield. In the past, these two things were almost mutually exclusive in DeFi—money would either be used for market making or for lending and yield, making it difficult to manage both at once. DualPool breaks down that wall.

Stablecoin exchange is the main battleground

This design is especially useful for stablecoins. The exchange rates among stablecoins are almost always clustered around $1, and the price ranges are very narrow—meaning at any moment, the vast majority of liquidity sits idle there waiting for a rare trade. Previously, this was pure waste; now, at least this money can earn yield.

Spark is a lending and savings protocol in the MakerDAO (now renamed Sky) ecosystem. As early as June, it moved $150 million in stablecoin liquidity onto Uniswap v4, covering USDS, USDT, and PYUSD, and using USDS as the quoted base asset. This batch of capital supported about $1.5 billion in stablecoin trading volume over 30 days.

Spark is building stablecoin infrastructure on Uniswap. They’ve just moved $150 million of liquidity into the protocol, which is one of the largest migrations in DeFi history. (Uniswap official statement)

Spark views this as the first phase of “Stablecoin FX Layer.” Its goal is to build on Uniswap v4 a deep liquidity pool shared by stablecoins from different issuers to capture institutional demand from players like PayPal, Visa, and Stripe that are rolling out stablecoins. As the number of stablecoin issuers increases, handling fragmented conversions becomes a problem—one shared conversion layer needs to solve exactly that.

After open-sourcing, anyone can deploy

DualPool has now completed its audit and been open-sourced, meaning it is no longer exclusive to Spark. Any team can use this Hook to deploy its own pool—customizing price ranges, choosing either single deposits or pooled deposits—then applying it to stablecoin pairs, or even to more volatile asset pairs.

Of course, adding another layer of yield vault also means adding another layer of smart-contract risk. Audits can reduce doubts, but they never equal security guarantees. Since the Uniswap v4 Hook mechanism went live, there haven’t been many large-scale instances that truly run at scale; DualPool is one of them. Whether idle capital can earn yield has been discussed for years in DeFi—this time, $150 million has finally been put up for real-world testing.

Frequently asked questions

What is Uniswap’s DualPool Hook?

DualPool is the open-source Uniswap v4 Hook jointly developed by Uniswap Labs and Spark. It lets a market maker’s idle liquidity first be deposited into an ERC-4626 yield vault to earn interest; only when trades touch the price range does it pull liquidity back into the pool for matching, enabling LPs to earn both trading fees and vault yield. It completed its audit and was open-sourced in July.

Why did Spark move $150 million to Uniswap v4?

Spark wants to build a stablecoin exchange layer (Stablecoin FX Layer) and make idle stablecoin liquidity earn yield via DualPool. The $150 million migrated in June covers USDS, USDT, and PYUSD, and it supported about $1.5 billion in trading volume within 30 days—one of the largest liquidity migrations in DeFi history.