The basic measure for evaluating the performance of capital investments is the return on investment (ROI), which always is expressed as a percent. To calculate ROI, the amount of return is divided by the amount of capital invested:

ROI% = return/capital invested

ROI is always for a given period of time—one year unless clearly stated otherwise. Return is a generic term and means different things for different investments. For investments in marketable securities, return includes cash income received during the period and the increase or decrease in market value during the period. The ROI on an investment in marketable securities is negative if the decrease in market value is more than the cash income received during the period.