Expected Cost of Equity and the Expected Risk Premium in the UK

University of Exeter Business School Discussion Paper No. 10/08

40 Pages Posted: 13 Jan 2011

See all articles by Alan Gregory

Alan Gregory

University of Exeter - Xfi Centre; University of Exeter Business School

Date Written: October 12, 2010


In this paper, it is argued that previous estimates of the expected cost of equity and the expected arithmetic risk premium in the UK show a degree of upward bias. Given the importance of the risk premium in regulatory cost of capital in the UK, this has important policy implications. There are three reasons why previous estimates could be upward biased. The first two arise from the comparison of estimates of the realised returns on Government Bond (“Gilt”) to realised and expected returns on equities. These estimates are frequently used to infer a risk premium relative to either the current yield on index-linked gilts or an “adjusted” current yield measure. This is incorrect on two counts; first, inconsistent estimates of the risk free rate are implied on the right hand side of the CAPM (Jenkinson, 1993); second, they compare realised returns from a bond which carried inflation risk with realised and expected returns from equities which may be expected to have at least some protection from inflation risk. The third, and most important, source of bias arises from uplifts to expected returns. If markets exhibit “excess volatility” (Shiller 1981), or if part of the historical return arises because of revisions to expected future cash flows, then estimates of variance derived from historical returns or price growth must be used with great care when uplifting average expected returns to derive simple discount rates. Adjusting expected returns for the effect of such biases leads to lower expected cost of equity and risk premia than those that are typically quoted.

Suggested Citation

Gregory, Alan, Expected Cost of Equity and the Expected Risk Premium in the UK (October 12, 2010). University of Exeter Business School Discussion Paper No. 10/08, Available at SSRN: https://ssrn.com/abstract=1738904 or http://dx.doi.org/10.2139/ssrn.1738904

Alan Gregory (Contact Author)

University of Exeter - Xfi Centre ( email )

University of Exeter
Xfi Building, Rennes Dr.
Exeter, EX4 3BZ
United Kingdom

University of Exeter Business School ( email )

Streatham Court
Xfi Building Rennes Dr.
Exeter, EX4 4JH
United Kingdom

Do you have a job opening that you would like to promote on SSRN?

Paper statistics

Abstract Views
PlumX Metrics