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Balancer: score, security record and what it is for

62/100SCORE · CCaution Grade C, fair

Balancer pioneered weighted pools, letting a pool hold assets in any ratio rather than fifty fifty. On 3 November 2025 attackers exploited a rounding direction error in v2 Composable Stable Pools and drained over 100 million dollars across nine chains, compounding thousands of tiny discrepancies into a very large loss. The contracts had been audited repeatedly. Balancer v3 uses different logic and was not affected, but several v2 forks were.

The facts

LIVE SINCE: 2020
TYPE: AMM, weighted pools
CHAINS: Ethereum, Arbitrum, Polygon, Base and more
SWAP FEE: Set per pool by the pool creator.
AUDITS: Audited repeatedly, which did not prevent the November 2025 exploit.
WHO CAN CHANGE IT: veBAL vote escrowed governance.

How the score breaks down

security12/30

liquidity14/25

chains12/15

costs12/15

decentralisation12/15

Where it is strong and where it is not

✓ Strengths

Weighted pools allow structures no other AMM offers
v3 was not affected by the 2025 exploit
Genuinely decentralised governance

✗ Weaknesses

Lost over 100 million dollars in November 2025 from repeatedly audited contracts
The affected v2 design is still widely forked elsewhere
Liquidity has not recovered to previous levels

Exploit history

2025

Over 100 million dollars, reported between 110 and 128 million, was drained from Balancer v2 Composable Stable Pools across nine chains on 3 November. The cause was a rounding direction error exploited through thousands of tiny transactions that compounded. Balancer v3 was not affected, and several forks of v2 were.

Our read

The most instructive entry in this directory. Balancer v2 was audited many times over five years and still lost more than 100 million dollars to a rounding error. Audits reduce risk, they do not remove it, and time in production is evidence rather than proof. Scored down heavily and listed anyway, because the lesson matters more than the protocol.

BEFORE YOU SWAP

Swap keeps failingSlippage, approvals, taxes and thin liquidity. Revoke approvalsEvery swap leaves a permission behind. Clear them. Gas tokensWhy you need the chain's native coin first. Pick a walletYou need self custody before you can use any DEX.

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