How Raydium's AMM Works on Solana

Raydium is a hybrid automated market maker (AMM) on Solana: it runs a standard constant-product AMM for swaps, but its defining feature is that it shares pool liquidity onto an on-chain central limit order book (CLOB) as limit orders, so the same liquidity serves both swap and order-book traders [Source: https://github.com/raydium-io/raydium-amm/blob/master/README.md].

1. The AMM core: constant-product pools

Raydium's AMM is an on-chain smart contract based on the "constant product" model (the same x·y = k invariant used by Uniswap-style AMMs), running permissionlessly on Solana. Per Raydium's own repo: "The Raydium AMM is an on-chain smart contract based on the 'constant product' in a permissionless and decentralized manner built on the Solana blockchain." Users deposit two tokens into a pool and receive LP tokens; swaps move along the constant-product curve, and the marginal ("spot") price is set by the pool's reserve ratio. The mainnet AMM program is deployed at 675kPX9MHTjS2zt1qfr1NYHuzeLXfQM9H24wFSUt1Mp8 [Source: https://github.com/raydium-io/raydium-amm/blob/master/README.md].

2. The order book integration (the differentiator)

What sets Raydium apart from a pure AMM is that it shares its pool liquidity onto a CLOB as limit orders. From the same repo: "it also shares its liquidity according to the Fibonacci sequence in the form of limit orders on OpenBook, the primary central limit order book (CLOB) of Solana." In practice, a pool's reserves are distributed across multiple price levels on the order book (spaced per the Fibonacci sequence), so traders can hit resting limit orders rather than only trading against the AMM curve [Source: https://github.com/raydium-io/raydium-amm/blob/master/README.md]. This is why Raydium is described as a hybrid AMM — combining AMM flexibility with order-book depth [Source: https://www.kraken.com/learn/what-is-raydium-ray].

3. The Serum → OpenBook history

Raydium launched in February 2021 as Solana's first AMM, originally leveraging Serum's central order book [Verified: launch date and "first AMM" status confirmed by Kraken's independent article — https://www.kraken.com/learn/what-is-raydium-ray]. The litepaper describes an AMM that "leverages the central order book of the Serum decentralized exchange (DEX) to enable lightning-fast trades, shared liquidity and new features for earning yield" [Source: https://s2.tokeninsight.com/static/content/whitepaper/Raydium-Litepaper+(2).pdf].

After Serum's collapse, Raydium integrated with OpenBook, the community-led fork of Serum V3, in November 2022 to continue sharing liquidity [Source: https://tokeninsight.com/en/news/solana-based-amm-raydium-integrates-with-serum-v3-fork-open-book]. [Note: Date not independently confirmed; see https://docs.raydium.io/protocol-overview/architecture] The OpenBook program address is srmqPvymJeFKQ4zGQed1GFppgkRHL9kaELCbyksJtPX [Source: https://github.com/raydium-io/raydium-amm/blob/master/README.md]. Note that the "order book" today refers to OpenBook (and its ecosystem), not the defunct Serum.

4. Current scale and evolution

[Source: https://dexpaprika.com/solana/raydium]

Raydium has evolved beyond the original constant-product AMM into multiple pool types: standard pools, Concentrated Liquidity (CLMM), and CPMM (v4), plus Farm, LaunchLab, and AcceleRaytor products [Source: https://docs.raydium.io/index.md]. In January 2025, Raydium integrated with Orderly Network to launch Solana perpetual futures, becoming the first DEX within that omnichain orderbook — a separate, newer order-book integration distinct from the OpenBook AMM sharing [Verified: integration and launch date confirmed by independent sources — https://solanacompass.com/projects/raydium, https://docs.raydium.io/products/perps; the "first DEX" claim comes from the press release and is not independently confirmed — https://www.globenewswire.com/news-release/2025/01/09/3007292/0/en/Raydium-Integrates-With-Orderly-Network-to-Launch-Solana-Perpetual-Futures.html].

Bottom line

Raydium's AMM works like a standard constant-product AMM for swaps, but its signature mechanism is routing a portion of pool liquidity onto Solana's on-chain CLOB (OpenBook) as Fibonacci-spaced limit orders. This hybrid design lets one pool serve both swap and order-book traders, deepening liquidity and improving price execution. The order book component has migrated over time (Serum → OpenBook) and now also extends to perps via Orderly.

Caveats: The exact Fibonacci spacing and current CLMM/CPMM parameters are not fully detailed in the sources retrieved; the "constant product + Fibonacci order book" description comes from Raydium's own GitHub README (first-party), corroborated by the litepaper abstract and third-party explainers. Scale figures are a DexPaprika snapshot and will vary over time.