Ever since Markowitz introduced the concept of portfolio theory in 1952, one of the questions predominant in the minds of financial theorists has been the constituency of the investor's optimal asset portfolio. Research into this area, which became known as capital market theory, attempted to analyze the equilibrium relationships between assets. One of the products of this research was the widely accepted Capital Asset Pricing Model (CAPM) of Sharpe and Lintner.

Gabriel A. Hawawini, Ashok Vora, Evidence of Intertemporal Systematic Risks in the Daily Price Movements of NYSE and AMEX Common Stocks, The Journal of Financial and Quantitative Analysis, Vol. 15, No. 2 (Jun., 1980), pp. 331-339

In this comment to a paper by Levhari and Levy published in this journal on February 1977 we provide evidence that shows that their conclusion does not hold if one applies the model to a large sample of common stocks.

This paper traces the historical developments of the efforts to find simple and accurate methods of approximating an annuity's implicit yield and a bond's yield to maturity. It is shown that the little known history of yield approximations is nevertheless very rich, with contributions dating as far back as the late seventeenth century. It is also shown that the standard textbook approximation formula for the bond's yield to maturity is the least accurate of a large family of formulas, some of which were suggested as early as 1855.