The study aims to compare the effects of employing investment deposits (joint and specified investment deposits) in Islamic banks, and investment deposits (term deposits and deposits with notification) at conventional banks, on shareholders’ profitability, represented by the earnings per share (EPS), in light of operational profits as a controlling variable. Data related to the study variables was collected from the annual financial reports published by the study sample banks, during the period (2009-2018). The study relies on multiple regression to test the hypotheses of the study. The high adjusted R² to explain the change in EPS for Islamic banks model as compared to conventional banks, is a result of the high difference between investment deposits (specified and joint) at Jordanian Islamic banks and investment deposits (term deposits and deposits with notification) at Jordanian conventional banks. The study found that it is important for the managements of Islamic banks to adopt a uniform method to combine speculative funds, in order to develop and improve shareholders’ profitability. The study recommended Islamic banks to follow practical, methodological and transparent approaches to calculate the rates of Murabaha profit margins between shareholders and depositors, while also taking into consideration some of the issues which could be harmful for the competition between Islamic and conventional banks.