Purpose The purpose of this paper is to investigate whether the Islamic religious occasions can, through their impact on investor sentiment, affect returns in six Arab financial markets. Design/methodology/approach In this paper, the authors test the effect of the occasions of Hajj pilgrimage, Ramadan, Eid-al-Fitr, Mawlid and Ashura during the period of 2001-2016 on Saudi Arabia, Dubai, Kuwait, Egypt, Qatar and Bahrain financial markets. Three measures of investor sentiment are used: trading volume, high minus low and psychological line index. Findings Higher effect of investor sentiment on returns is detected after Hajj pilgrimage than that before Hajj pilgrimage in all studied financial markets. The positive emotions during Ramadan contribute significantly to the increase in returns in Arab financial markets. Results indicate that most of studied financial markets exhibit a significant effect of investor sentiment on returns during the first 10 days and the second 10 days of Ramadan. Empirical results indicate that Eid-al-Fitr affects the relation between investor sentiment and returns in Saudi Arabia, Kuwait, Qatar and Dubai financial markets. Relationship between investor sentiment and returns is not is not significantly affected by the Mawlid occasion, except in the Dubai and Kuwait financial markets. Originality/value The Islamic occasions of the Hajj pilgrimage, Ramadan and Eid-al-Fitr affect significantly the relation between investor sentiment and returns.