the rate that the investor must earn for certain to give up the use of his money.

the rate that a risk-free investment would need to offer with certainty to be considered equally attractive as the risky portfolio.

represented by the scaling factor "-0.5" in the utility function.

the rate that equates "A" in the utility function with the average risk aversion coefficient for all risk-averse investors.

the minimum rate guaranteed by institutions such as banks.