The Role of Recency Bias in Forming Momentum Pattern; Evidence from Tehran Stock Exchange

Studies have shown that price trends such as momentum in the stock market form opportunities for abnormal returns. The underreaction of investors to reference points, due to behavioral bias, is one of the reasons for forming momentum. In this research, the role of recency bias in forming momentum pattern is investigated.

Research is a ex-post facto research that is carried out using a portfolio study method and data obtained from 108 companies from Tehran Stock Exchange during the 10 years from the beginning of 1386 to the end of 1395 (Solar Hijri-Iranian calendar) and selecting the three reference prices including 13-, 26- and 52-week high prices. Also, robustness tests based on Fama-French multi-factor model and Fama-MacBeth model.

Momentum strategies based on 13, 26 and 52-week reference prices in the portfolios of 20% winner-loser stocks are 0%, 8.2%, and, 8.1%, respectively, the latter two being statistically significant. With 3 and 6-month echo periods, the strategy of the 26-week high at portfolio levels is significant and this return is maintained by adjusting the risk factors. The results were evaluated by robustness tests and the evidences indicate that the findings are significant in the presence of control variables.

results showed momentum strategy based on 26-week high price due to recency bias (that is defined by recency ratio) has a higher performance compared to other reference prices that can be explained by the phenomenon of updating reference points.It also improves with increasing echo effect.

In this study, the role of the recency bias and the echo effect with the three reference prices is examined and the 26-week high price is considered as a notable reference price which along with other reference prices in theory (such as a 52-week high price) can be used to define the momentum strategy.