Culper Research Shorts Ether and BitMine, Warns Fusaka Upgrade Cut Ethereum Fees 90%

Culper Research disclosed a short position on ether (ETH) and ETH-linked shares including BitMine (BMNR) on Thursday, saying Ethereum's December 2025 Fusaka upgrade flooded the network with excess blockspace and cut transaction fees roughly 90%. The firm said lower fees have reduced validator staking yields, which it claims could trigger a feedback loop where weaker returns curb staking demand and erode network security. Lookonchain data show Ethereum cofounder Vitalik Buterin sold nearly 20,000 ETH this year, worth about $40 million at current prices, while BitMine chairman Tom Lee remains bullish based on rising transaction counts and active addresses; Culper argued those metrics are distorted by address poisoning attacks. The firm extended its short thesis to BitMine, which has accumulated roughly 4.4 million ETH since July and is sitting on about $7.4 billion in unrealized losses with holdings estimated 45% underwater, according to DropsTab figures; BitMine did not respond to a request for comment.