Your broker called earlier today and offered you the opportunity to invest in a security. As a friend, she suggested that you compare the current, or present value, cost of the security and the discounted value of its expected future cash flows before deciding whether or not to invest. The decision rule that should be used to decide whether or not to invest should be:

Everything else being equal, you should invest if the discounted value of the security's expected future cash flows is greater than or equal to the current cost of the security.

Explanation:

You would use the capital budgeting technique known as net present value (NPV) . In order for a project or investment to be accepted, the sum of the present values of future cash inflows generated by the project should be greater than the initial amount invested or the initial cost. If the PV of the future cashflows is lower than the initial cost of capital, the investment would be rejected. On the other hand, if they are equal, the investor would be indifferent between accepting or rejecting the investment.