RT Journal Article SR Electronic T1 Cryptocurrency Value and 51% Attacks: Evidence from Event Studies JF The Journal of Alternative Investments FD Institutional Investor Journals SP jai.2019.1.081 DO 10.3905/jai.2019.1.081 A1 Savva Shanaev A1 Arina Shuraeva A1 Mikhail Vasenin A1 Maksim Kuznetsov YR 2019 UL https://pm-research.com/content/early/2019/10/30/jai.2019.1.081.abstract AB In this article, an event studies approach is utilized to assess the influence of 51% attacks on proof-of-work (PoW) cryptocurrency prices. The study uses an exhaustive sample of 14 individual attacks on 13 cryptocurrencies. Across multiple event studies techniques, majority attacks on blockchains are consistently shown to immediately decrease corresponding coin prices by 12% to 15%. Significantly negative price response is robust in various event windows. Coin prices do not recover to pre-attack levels one week after the event. There is evidence of pump-and-dump schemes prior to the 51% attack, however the market demonstrates high efficiency after the attacks. 51% attacks are suggested to be a fundamental risk factor for cryptocurrency investments, primarily characteristic of small PoW coins with low hash rates.TOPIC: CurrencyKey Findings• 51% attacks on Proof-of-Work cryptocurrencies decrease their market prices by 12.60% on average.• The effect is robust to different measurement techniques and in various event windows.• There is evidence of insider trading and “pump-and-dump” schemes prior to the attacks.