Cryptocurrency value and 51% attacks: evidence from event studies

Research output: Contribution to journalArticle

DOI

Authors

External departments

  • University of London

Details

Original languageEnglish
Pages (from-to)65-77
Number of pages13
JournalJournal of Alternative Investments
Volume22
Issue number3
Early online date30 Oct 2019
DOIs
Publication statusPublished - 31 Dec 2019
Publication type

Research output: Contribution to journalArticle

Abstract

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.