Praise be to Allah, and may Allah’s peace and blessings be upon the Messenger of Allah, his family and his companions. Wa alaikum assalam wa rahmatullahi wa barakatuh. As to what follows: In response to your question, we say:   The investment funds owned by a person consist of units. Thus Zakat is due on them based on the value of these units, regardless of whether it is high or low,  because in reality they are trade goods which are bought and sold. Therefore, they are not affected by the lowness or highness of their value. When the time for Zakat comes the investor  should calculate the value of the investment fund either by knowing the number of units and their value or asking the company about the value of his investments, and then give Zakat based on the money that he has in these funds.