Balancer is a programmable AMM for weighted Ethereum liquidity

Bottom line: Ethereum automated market maker protocol for swaps and liquidity, built around weighted pools that hold custom token ratios beyond simple.

Balancer is a programmable automated market maker for weighted liquidity pools, where one pool holds custom token ratios such as 80/20, 60/20/20 or a standard 50/50 pair. It runs through smart contracts that price swaps, account for deposits, mint pool shares and collect fees without a central market maker. Its main draw is flexibility: liquidity providers choose exposure, builders create specialized pool types and traders route through pools holding fungible and yield-bearing assets.

Weighted pools turn token ratios into market structure

The signature design is the weighted pool. A conventional constant-product pool pairs two assets in equal weights; this design supports pools with several tokens and custom weights that sum to 100%. An 80/20 WETH or WBTC pool leaves most exposure in one asset while still offering a market for swaps. A 60/20/20 pool spreads liquidity across three assets while keeping a defined target composition.

Those weights matter. A higher weight gives that token deeper effective liquidity and lower relative price impact inside the pool. A lower weight makes that side thinner, so large trades move the pool price faster. Standard weighted pools in v3 support up to eight tokens at the Vault level, with a minimum token weight of 1% and swap limits designed to keep pool math inside secure bounds.

How the Vault, routers and pools settle a trade

Inside Balancer v3, the Vault centralizes token accounting while pool contracts focus on pricing math. A router receives the user action, unlocks the Vault for that transaction, calls the relevant pool calculation and then settles every credit and debt before the transaction finishes. If the settlement does not balance, the transaction reverts.

This architecture separates three jobs that many AMMs bundle together. The router is the user-facing path for swaps, adding liquidity and removing liquidity. The Vault tracks balances and enforces final settlement. The pool contract defines the invariant, such as weighted math or stable math, that decides the trade output or liquidity movement.

Where swap fees, yield fees and creator fees accrue

Balancer v3 uses fee mechanics at both the pool and protocol level. Weighted pool swap fees sit within bounded ranges, and v3 documentation describes a protocol model with a universal 50% protocol share of swap fees and a reduced 10% protocol share of yield fees for yield-bearing structures. Pool creators also have a fee concept for custom deployments where the pool design includes it.

Swap fees compensate liquidity providers for making markets, while protocol fees fund the DAO Treasury under the post-2026 model. Traders see the pool fee in the quoted route, then pay network gas separately. Liquidity providers receive fee exposure through their pool position rather than through a separate manual claim for each trade.

Pool tokens, BPT and the liquidity provider position

A deposit mints Balancer Pool Tokens, commonly shortened to BPT. These ERC20-compatible tokens represent a proportional claim on a pool's assets and accumulated trading fees. When a provider exits, the BPT is burned and the underlying tokens are returned according to the pool's current composition and the exit method selected.

BPT also makes positions composable. Other DeFi systems read ERC20 balances, so pool shares fit into dashboards, collateral designs and routing logic. That composability requires sound oracle design, because a pool share price depends on underlying token prices, pool math and the state of the Vault during a transaction.

BAL governance after the 2026 tokenomics revamp

The BAL token gives Balancer governance its voting asset. In Q2 2026, approved governance changes halted ongoing BAL emissions, discontinued veBAL and shifted voting power to raw BAL across supported production chains. Protocol fees now route to the DAO Treasury, and major decisions such as new pool factories, new chain deployments and supply changes continue through token-holder governance.

That change matters for readers who remember the older gauge and veBAL system. The historical emissions model no longer describes the current token economy. BAL remains the governance token, while liquidity incentives and fee direction follow the newer framework approved through governance.

Stable, boosted and launch pools for specific liquidity jobs

Weighted pools are only one part of the system. Stable pools serve assets expected to trade close together, such as stablecoins or correlated liquid staking tokens, using math built for lower slippage around a tight price range. Boosted pools combine AMM liquidity with yield-bearing assets, using wrappers and rate providers to account for assets that accrue value over time.

This is where Balancer moves beyond a single pool formula. Liquidity Bootstrapping Pools support token distribution and price discovery by changing weights over time. Gyroscope-style pools bring specialized curve designs. Hooks in v3 extend existing pool types with extra logic, including dynamic swap fees, limits, automatic actions and other behaviors set when a pool is registered.

Starting with a swap or a pool deposit

A first Balancer swap starts like any DeFi trade: connect a self-custody wallet, choose the input token, review the output quote, approve the token if required and submit the transaction. The router handles the interaction with the Vault and pools, while the wallet shows token approval, gas and final transaction signing.

Adding liquidity takes more judgment because the provider chooses a pool position rather than a single trade. Before depositing, review:

• the pool assets and their target weights;
• the swap fee and recent volume;
• whether the pool uses weighted, stable, boosted or custom math;
• the expected token mix when entering and exiting;
• the network gas cost and any token approval already granted.

Single-token joins and exits exist in some routes, but the pool math converts that action into the pool's required accounting. A proportional deposit keeps the position closest to the existing pool balance.

Risks that matter in weighted AMM pools

More broadly, Balancer reduces manual market making, yet AMM risk remains concrete. Impermanent loss appears when the pool's asset prices move away from the value of simply holding the same tokens. Asymmetric weights change that exposure: an 80/20 pool keeps more exposure to the heavier asset, while the lighter side has less depth and more slippage on large trades.

Smart contract risk also differs by pool type. A plain weighted pool has a simpler surface than a custom pool with hooks, external rate providers or yield-bearing wrappers. Thin liquidity, stale assumptions about correlated assets and large price moves all affect execution quality. The clearest warning sign is a route where the quoted price impact overwhelms the fee advantage.

Uniswap, Curve and Gyroscope as nearby reference points

Day to day, Balancer is strongest when custom weights, multi-token pools or programmable pool behavior matter. Uniswap is the better-known reference for concentrated liquidity and simple token pairs. Curve is closely associated with stablecoin and correlated-asset liquidity. Gyroscope contributes specialized pool designs that also appear in this ecosystem.

The useful comparison is not a winner-takes-all ranking. A trader wants the best route after price impact, fees and gas. A liquidity provider cares about asset exposure, pool math and volume. A builder looks for the architecture that supports the market they are creating. Weighted AMM design gives this protocol a distinct place among those choices.