canonical_beacon_block_attester_slashing stores two attesting-index arrays for every proof. Summing those arrays across mainnet gives 245,290 validator-index positions. The protocol intersected them into 555 overlap positions, covering 554 unique validators. The arrays are evidence, not a validator-slashing counter.
On September 10, 2025, a single Ethereum validator holding 2,020 ETH double-signed an attestation. By any historical measure, the damage should have been severe. Under the rules in place before Pectra, an initial slashing penalty of that scale would have wiped out tens of ETH in one epoch.
Instead, the validator lost roughly 5.53 ETH total — about 0.27% of its stake — and withdrew 2,015 ETH on October 28, intact. The new Electra slashing formula had been tested in the wild, and it worked exactly as designed.
Pectra introduced MAX_EFFECTIVE_BALANCE — letting validators hold up to 2,048 ETH instead of a hard cap of 32. On May 8, 2025, the day after Pectra went live, Abyss Finance consolidated 60+ validators into a single mega-validator with nearly 2,020 ETH of stake. Four months later, on September 10, it was slashed.
This is the first time a MaxEB compounding validator has been slashed on Ethereum mainnet. The data tells an interesting story — not because the penalty was catastrophic, but because of exactly how gentle it was.