Balancer has just published its preliminary report on the attack that shook the DeFi protocol on November 3. A technical flaw in V2 pools allowed hackers to siphon $128 million across seven different blockchains. But the real bill turns out to be much higher: the total value locked (TVL) collapsed by 58% in just two days. How could a protocol audited eleven times be the victim of such a debacle?
In brief
- Balancer lost $128 million on November 3 due to a rounding error in its V2 pools.
- The protocol's TVL collapsed by 58%, from $443 million to $186 million in two days.
- Seven blockchains were affected, including Ethereum which represents 99 million losses.
- Ethical hacker teams have recovered $33 million so far.
A microscopic flaw with devastating consequences
On November 3, 2025, Balancer joins the very exclusive club of DeFi protocols victims of massive hacks. The culprit? A trivial rounding error hidden in the “composable stable pools V2”.
This flaw gave attackers an avenue to manipulate batch trades and methodically drain liquidity.
Ethereum suffered the most violent shock with 99 million dollars embezzled. The attackers then targeted Base, Polygon, Arbitrum, Optimism, Sonic and Avalanche. Their method? Play with batch swaps to distort balance calculations and extract value before the systems detect the anomaly.
Balancer's reaction was quick. The team suspended the vulnerable pools within minutes of detection. This intervention prevented the bleeding from getting worse. The V3 pools remained completely intact, confirming the solidity of the new protocol infrastructure.
Recovery efforts are progressing. Ethical hackers have already repatriated 33 million dollars. Berachain carried out a hard fork and recovered 12.8 million, with refunds already underway.
StakeWise managed to save 20 million thanks to its own operations. The protocol praised “the speed which made it possible to avoid more significant hemorrhage”. A full report will be released soon with recovery steps for affected users.
The collapse of trust costs more than the hack
The TVL figures tell an even starker story. Balancer's total locked value literally collapsed. It went from $443 million on November 3 to just $186 million today. A dizzying drop of 58% in forty-eight hours.
This tumble erases months of relative stability. Since January 2025, Balancer was already losing ground, its TVL having fallen by more than a billion. The hack simply accelerated this downward trend and scared away investors. The total loss now exceeds $257 million if we add the theft and capital flight.
The BAL token plunged 6% before stabilizing. Traders quickly recognized the resilience of version 3 of the protocol. This price resistance, greater than that of the TVL, demonstrates a certain market confidence in Balancer's recovery capacity.
The protocol is now pushing an aggressive migration to V3. The team also warns of fraudulent messages that exploit post-hack confusion. Deeper audits and code updates are promised to prevent history from repeating itself.
This hack of 128 million propels Balancer to second place on the unenviable podium of the biggest DeFi hacks of 2025. The ecosystem thus crosses the mark of 2.2 billion dollars in annual losses.
A stark reminder that DeFi, despite its promises of transparency and security, remains a minefield. Composability, this founding principle which allows protocols to fit together like Lego, shows its downside here: when one link gives way, the whole chain falters.
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