Abstract: Ethereum blockchain is optimizing for ETH to become digital money by undergoing frequent upgrades to improve its fundamentals, which are market-moving events containing implementation risk, often dividing investors in crypto markets. Understanding these dynamics is crucial as digital assets become increasingly integrated with traditional finance. Employing an event study analysis, I find that investors react predominantly positively to upgrades that directly impact the efficiency of the blockchain, while those associated with the transition from proof-of-work to proof-of-stake are largely associated with negative average abnormal returns, likely reflecting perceived implementation risk. The findings highlight low market efficiency, driven by the novelty and technical complexity of the upgrades. Sector-specific analysis highlights the interconnectedness of crypto markets via market-wide spillovers.