Atomic Swaps Explained: How Multi-Protocol Trades Actually Execute in DeFi

By Jamie McCormick, Co-CMO, Stabull Labs

The sixth article in the 15 part “Deconstructing DeFi” Series.

⸻

To understand why Stabull is being pulled into these transactions, it helps to understand how atomic swaps actually work end to end.

What “atomic” really means in DeFi

In an EVM-based blockchain such as Ethereum or Base, every transaction is executed as a single, indivisible unit.

Either:

• every step in the transaction succeeds, or
• the entire transaction reverts as if it never happened

There is no partial completion, no intermediate state, and no possibility of funds being left “in limbo.”

This property is what allows multiple protocols — often written by different teams, with different incentives — to interact safely within a single transaction.

From user intent to execution path

Most atomic swaps do not begin with a trader manually choosing each step. Instead, they begin with a simple intent:

“I want to swap asset A for asset B, as efficiently as possible.”

From there, execution systems — such as solvers, aggregators, or automated trading bots — determine how to achieve that outcome.

The resulting execution path might involve:

• multiple swaps across different venues
• temporary borrowing of liquidity
• intermediate conversions through stablecoins or FX pairs
• fee payments to multiple protocols

All of this happens inside a single transaction.

Flash liquidity and capital efficiency

A common feature of atomic execution is the use of flash liquidity.

Flash loans allow a transaction to borrow assets with no upfront collateral, provided the borrowed amount (plus a small fee) is repaid before the transaction completes. If repayment fails, the entire transaction reverts.

This enables:

• large trades without idle capital
• arbitrage across venues
• complex rebalancing strategies

In the transactions we reviewed, flash liquidity often appeared briefly at the beginning of the transaction and disappeared again at the end — never existing outside that atomic context.

Where Stabull fits into atomic execution

Within these multi-leg transactions, each protocol is used for what it does best.

Volatile asset swaps might occur on AMMs optimised for price discovery. Stablecoin conversions might occur on venues with deep, low-slippage pools. FX or RWA legs require pricing that reflects off-chain reality.

This is where Stabull appears.

Rather than acting as a destination, Stabull is frequently used as:

• a stable execution leg
• an FX conversion point
• a pricing reference for real-world–anchored assets

Because pricing is oracle-anchored, execution through Stabull can be trusted not to drift significantly during the transaction — a critical property when many steps depend on each other.

Atomicity removes counterparty risk

One of the most important consequences of atomic execution is the removal of counterparty risk.

No participant in the transaction needs to trust any other participant beyond the guarantees provided by the blockchain itself. If any step fails — a pool has insufficient liquidity, a price moves unfavourably, or a fee cannot be paid — the transaction simply does not happen.

This is why sophisticated actors are comfortable routing trades through unfamiliar protocols. They are not taking incremental risk by doing so.

For Stabull, this means being used inside atomic swaps does not require prior relationships, agreements, or integrations. It requires only that execution is reliable.

Why atomic execution drives non-UI volume

Atomic swaps are not initiated by users clicking buttons. They are initiated by systems reacting to market conditions.

As a result:

• volume is repeatable rather than episodic
• trades occur whenever conditions are met, not when users are active
• fees accrue quietly but consistently

This explains why non-UI volume can grow even when visible activity appears unchanged.

Once a protocol is embedded in execution paths, it benefits from all the activity upstream and downstream of it.

The invisible backbone of DeFi

The transactions we traced made something clear: atomic execution is the invisible backbone of DeFi.

Users see the beginning and the end of a trade. What happens in between is increasingly complex, automated, and optimised across multiple protocols.

Stabull’s growing role inside these atomic paths suggests it is being treated not as a niche exchange, but as a dependable component in a broader execution system.

In the next article, we’ll focus on one of the most misunderstood participants in that system: arbitrage bots, and why their presence is not something LPs should fear — but something they are paid for.

About the Author

Jamie McCormick is Co-Chief Marketing Officer at Stabull Finance, where he has been working for over two years on positioning the protocol within the evolving DeFi ecosystem.

He is also the founder of Bitcoin Marketing Team, established in 2014 and recognised as Europe’s oldest specialist crypto marketing agency. Over the past decade, the agency has worked with a wide range of projects across the digital asset and Web3 landscape.

Jamie first became involved in crypto in 2013 and has a long-standing interest in Bitcoin and Ethereum. Over the last two years, his focus has increasingly shifted toward understanding the mechanics of decentralised finance, particularly how on-chain infrastructure is used in practice rather than in theory.