TY - JOUR T1 - Market Efficiency in ESG Indexes: Trading Opportunities JF - The Journal of Impact and ESG Investing SP - 72 LP - 82 DO - 10.3905/jesg.2021.1.016 VL - 1 IS - 4 AU - Richard Paul Gregory Y1 - 2021/05/31 UR - https://pm-research.com/content/1/4/72.abstract N2 - Examining the returns of 16 ESG indexes, we found evidence that a few violate the conditions of weak-form efficiency and that all violate conditions for semi-strong form efficiency. Given previous research on market efficiency in the ESG market, this points to profitable trading opportunities in this market using public information. We also discuss why these results are not subject to previous criticisms of testing of market efficiency.TOPICS: ESG investing, mutual funds/passive investing/indexing, portfolio theory, financial crises and financial market historyKey Findings▪ We perform market efficiency tests of 32 indexes for 16 countries using the Hurst exponent.▪ In contrast to previous research, the tests find no difference in market efficiency between ESG and Standard indexes.▪ For all indexes, efficiency decreased during the Great Financial Crisis. ER -