The return on holding an investment for some period, say a year, is equal to any cash payment received due to the property, plus the change in market price, divided by the asking price. For example, you could buy a $100 security that would pay you $7 in cash and be worth $106 a year later.
The return would be ($7 + $6) / $100 = 13%. Thus, your return comes from two sources: income, plus any price appreciation (or price loss).
To begin managing risk, let's first consider a couple of examples. Suppose you buy a 1-year Treasury bond with a yield of 8%.
If you hold it year-round, you'll earn a government-guaranteed 8% investment return—no more, no less. Now, you buy a common share in any company and hold it for one year.
The cash dividend that you projected to receive may or may not materialize as expected. And, what is more, the price at the end of the year of the share may be much less than expected, perhaps less than at the beginning.
For risk-averse individuals, the difference between the certainty equivalent and the expected value of an investment constitutes a risk premium; this is the additional expected return that the risky investment must offer to the investor in order for this individual to accept the risky investment.
Note that in our example, the expected value of the risky investment had to exceed the safe offer of $3,000 by $2,000 or more for you to be willing to accept it.
Here we will take the generally accepted view that investors are risk averse.
This implies that risky investments must offer higher expected returns than less risky investments in order for people to buy and hold them.
(Keep in mind, however, that we're talking about expected returns; the actual return on a risky investment may be much less than the actual return on a less risky alternative. And, to have lower risk, you must be willing to accept investments that have lower expected returns.