Naeem Muhammad Abubakr, Bouri Elie, Peng Zhe, Shahzad Syed Jawad Hussain, Vo Xuan Vinh
School of Economics and Finance, Massey University, New Zealand.
Institute of Business Research, University of Economics Ho Chi Minh City, Ho Chi Minh City, Viet Nam.
Physica A. 2021 Mar 1;565:125562. doi: 10.1016/j.physa.2020.125562. Epub 2020 Nov 27.
In this study, we examine the asymmetric efficiency of cryptocurrencies using 1-hour data of Bitcoin, Ethereum, Litecoin, and Ripple. In doing so, we utilize the asymmetric multifractal detrended fluctuation analysis (MF-DFA). We find significant asymmetric multifractality in the price of cryptocurrencies and that upward trends exhibit stronger multifractality than downward trends. Using the time-varying deficiency measure, we show that the COVID-19 outbreak adversely affected the efficiency of the four cryptocurrencies, given a substantial increase in the levels of inefficiency during the COVID-19 period. Bitcoin and Ethereum are the hardest hit, and at the same time, these two largest cryptocurrencies recovered faster at the end of March 2020 from their sharp dip towards inefficiency. The findings confirm previous evidence that market efficiency is time varying; also, unprecedented catastrophic events, such as the COVID-19 outbreak, have adverse effects of on the efficiency of leading cryptocurrencies.
在本研究中,我们使用比特币、以太坊、莱特币和瑞波币的1小时数据来检验加密货币的非对称效率。在此过程中,我们运用了非对称多重分形去趋势波动分析(MF-DFA)。我们发现加密货币价格存在显著的非对称多重分形性,且上涨趋势比下跌趋势表现出更强的多重分形性。使用时变缺陷度量,我们表明,鉴于新冠疫情期间无效率水平大幅上升,新冠疫情爆发对这四种加密货币的效率产生了不利影响。比特币和以太坊受影响最严重,与此同时,这两种最大的加密货币在2020年3月底从急剧跌至无效率状态中恢复得更快。这些发现证实了之前市场效率随时间变化的证据;此外,像新冠疫情爆发这样前所未有的灾难性事件,会对主要加密货币的效率产生不利影响。