This paper deals with capital budgeting decisions under uncertainty. We present an Aggregate Return On
Investment (AROI), obtained as the ratio of total (undiscounted) cash flow to total invested capital and
show that it is a genuine rate of return which, compared with the risk-adjusted cost of capital, correctly
signals wealth creation. For choosing between two mutually exclusive projects, we derive an incremental
AROI and an incremental risk-adjusted cost of capital, by means of which two unequal-risk projects can
be correctly compared. Iterating the incremental procedure, we show that the AROI approach correctly
ranks any bundle of different-risk competing projects. Relations with other criteria such as Modified
Internal Rate of Return, average IRR, Cash Multiple, and Profitability Index are provided.
Theoretically, the AROI approach constitutes a link between arbitrage choice theory and corporate
investment theory, and shows that explicit discounting is not necessary for measuring economic
profitability. Practically, the AROI is a user-friendly, easy-to-compute rate of return derived from the
same set of data required by the net present value (NPV). Also, it does not incur the difficulties met by
the internal rate of return (IRR): in particular, it is unique and it is based on economically significant
capital values (i.e., market-driven values). As such, the AROI significantly expresses the efficiency of the
project's invested capital.