For years, Balancer has been one of the most trusted institutions in DeFi, a protocol that has survived several bear markets, audits, and integrations without scandal.
However, this credibility collapsed on November 3, when blockchain security firm PeckShield reported that Balancer and several of its forks were subject to an active exploit spreading across multiple chains.
In a matter of hours, more than $128 million disappeared, leaving behind a succession of dried-up pools, frozen protocols and shaken investors.
Data from PeckShield showed that the platform’s protocol on Ethereum suffered the heaviest losses, around $100 million. Berachain followed with $12.9 million, while Arbitrum, Base, and smaller forks such as Sonic, Optimism, and Polygon saw fewer but still significant thefts.
As the leak unfolded, Balancer acknowledged a “potential exploit affecting Balancer v2 pools,” stating that its engineering and security teams were investigating the issue with high priority.
However, this recognition has done little to slow withdrawals among integrators and forks.
By the end of the day, DeFiLlama data showed that Balancer’s total value locked (TVL) had decreased by 46% to approximately $422 million, down from $770 million at press time.
What happened?
Preliminary analyzes from blockchain security firm Phalcon indicated that the attacker targeted Balancer Pool Tokens (BPT), which represent users’ shares in liquidity pools.
According to the company, the vulnerability came from the way Balancer calculated pool prices during batch trades. By manipulating this logic, the exploiter distorted the evolution of internal prices, creating an artificial imbalance that allowed him to withdraw tokens before the system corrected itself.
Crypto analyst Adi wrote:
“Poor management of permissions and callbacks allowed the attacker to bypass protections. This enabled unauthorized trades or balance manipulations between interconnected pools, draining assets in rapid succession (within minutes).”
Meanwhile, Balancer’s composable vault architecture, long praised for its flexibility, amplified the damage. Since vaults could reference each other dynamically, the distortion carried over to interconnected pools.
Interestingly, Coinbase’s Conor Grogan pointed out that the attacker’s approach suggested professional sophistication.
Grogan noted that the attacker’s address was initially funded by 100 ETH from Tornado Cash, implying that the funds likely came from previous exploits.
“People don’t typically put 100 ETH into Tornado Cash for fun,” he wrote, suggesting the transaction pattern reflected an experienced and previously active hacker.
Collapse of DeFi trust
If the feat itself was technical, its impact was psychological.
Balancer has long been considered a conservative place for liquidity providers, a place to park assets and earn a modest but stable return. Its longevity, audits, and integrations across major DeFi platforms fostered the illusion that endurance equaled security. The November 3 breach destroyed this narrative overnight.
Lefteris Karapetsas, founder of crypto platform Rotki, called it a “collapse of trust” and not just a hack of the DeFi platform.
He denounced the fact that:
“A protocol in effect since 2020, audited and widely used, can still experience near-total TVL loss. This is a red flag for anyone who thinks DeFi is “stable”.”
This reaction reflects the general feeling. In a market that values self-custody and verifiable code, trust has quietly replaced trust as the hidden foundation of DeFi.
The failure of Balancer showed that even mathematically sound systems are vulnerable to unanticipated complexity.
Robdog, the pseudonymous developer of Cork Protocol, said:
“As (DeFi) foundations become more and more secure, the sad reality is that smart contract risk is all around us.”
Implications for DeFi
The Balancer exploit hit a sweet spot for decentralized finance, breaking a brief period of calm. As of October, total losses from hacks fell to an annual low of just $18 million, according to PeckShield.
However, with just one incident in November, this figure has already surpassed $120 million, making it the third worst month for DeFi breaches in 2025.
At the same time, this attack highlights a fundamental paradox at the heart of DeFi: composability, the functionality that allows protocols to connect and rely on each other, also amplifies systemic risk.
When a core protocol like Balancer goes down, the impact instantly ripples through the networks that rely on it.
On Berachain, validators have suspended block production to avoid contagion. Further protocols followed with temporary suspensions of loan and transition functions.
These quick reactions limited losses, but they also highlighted a broader truth that DeFi operates without the coordination mechanisms that support traditional finance.
In this space, there are no regulators, no central banks, no mandatory safety nets. Instead, crisis management relies heavily on developers and auditors working in tandem, often within minutes, to contain the consequences.
Considering this, Robdog said:
(It’s) a good reminder of why we need to develop better risk management infrastructure.
Beyond the immediate technical loss, the damage to trust may be more difficult to repair.
Every major exploit erodes trust in DeFi’s promise of self-regulated code. For institutional investors considering exposure to the sector, repeated failures indicate that decentralized markets remain experimental.
Karapetsas noted:
“No serious capital is allocated to such fragile systems.”
This perception is already shaping policy in the world’s major economies.
Suhail Kakar, a prominent Web3 developer, pointed out a sad reality in the wake of the Balancer exploit: even multiple high-level security audits cannot guarantee security in DeFi.
As he noted, Balancer has been the subject of more than ten audits, and its central storage contract has been reviewed by several independent firms; However, the protocol still suffered a major violation.
Kakar’s point highlights a growing sentiment in the industry that “audited by X” is no longer a mark of infallibility; rather, it reflects the inherent complexity and unpredictability of decentralized systems where even well-tested code can harbor invisible vulnerabilities.
US authorities are developing frameworks that would introduce regulations on DeFi protocols. Industry observers expect the Balancer exploit to accelerate these efforts, as policymakers grapple with the growing risk of continued integration between crypto and the traditional financial sector.
