Evidence for and Against the Validity of Efficient Market Hypothesis

Abstract

The concept of an efficient financial market, in literature known as efficient market hypothesis (EMH), has had a long and difficult development path from the idea itself to its final conception, as one of the central paradigms in modern finance. It has been tested and critically reviewed for decades, and the two basic types of problems it has encountered are theoretical paradoxes and market anomalies. The aim of the paper is to examine the validity of EMH through various financial market efficiency tests and the results of previous research. The intention is to answer the question of whether, despite theoretical paradoxes and market anomalies, the notion of validity can be attributed to the concept of an efficient financial market. In this regard, the paper presents plenty of evidence for and against the validity of weak, semi-strong, and strong form of EMH, to conclude that, even after more than half a century of research, financial literature has not reached a consensus on the presence or absence of the validity of this hypothesis