Lanstein and Sharpe (LS) attempt to explain residual covariances between stocks on the basis of duration considerations. The results, by admission are mixed. Rather than to focus on these per se, I would like to further the work by making some suggestions with respect to the formal model development and the empirical tests-on the basis that both could be made crisper and thereby increase the value of what already is a contribution.

Ezequiel L. Machado, Willard T. Carleton, Financial Planning in a Regulated Environment, The Journal of Financial and Quantitative Analysis, Vol. 13, No. 4, Proceedings of Thirteenth Annual Conference of the Western Finance Association, June 20-26, 1978 (Nov., 1978), pp. 759-777

The concept that corporate investment-growth decisions are constrained by a profit opportunities schedule is central to much of the literature on finance and the theory of the firm. These writings suggest that, for a single firm: (1) the profit opportunities schedule is a decreasing function of investment growth (the slope reflecting, inter alia, competitive conditions); (2) the schedule shifts to the right with changes in national income (except for a firm producing income-inferior goods), and (3) the schedule's position (intercept) at a moment in time reflects a host of factors that are summarized by the term “management.”

Dissatisfaction occasionally has been expressed with traditional measures of duration for immunization on conceptual grounds. However, more elegant duration measures have not been found to be superior to the traditional ones in empirical tests of immunization efficacy. Under the assumption that the term structure of continuously compounded interest rates can be expressed as a polynomial, Chambers and Carleton (1981) demonstrate that the finite and noninstantaneous return of a default-free bond can be expressed as a vector product of a duration vector and a shift vector. This study derives immunization strategies from the model and tests them. The results of the portfolio tests indicate that the traditional duration approach of Macaulay provides enhanced immunization relative to maturity approaches or naive approaches. However, the duration vector approach produces further improvements.

Donald R. Chambers, Willard T. Carleton, Donald W. Waldman, A New Approach to Estimation of the Term Structure of Interest Rates, The Journal of Financial and Quantitative Analysis, Vol. 19, No. 3 (Sep., 1984), pp. 233-252

Intelligent corporate financial planning has been necessary for as long as the corporate form of business enterprise has existed. Only in recent years, however, have computer technology and academic theorizing been harnessed to meet this practical need. Without wishing to minimize the impact and value of these efforts on the practice of corporate finance, we do think there are grounds for believing that the new finance “tools” have been less than maximally effective. In this article we contrast typical financial modeling theory in order to interpret the gap between the two. Then we describe a financial policy model whose characteristics might be expected to be more acceptable in practice. Finally, we discuss the implications of the theory/practice gap and our experience with this model for future scholarly activities in the modeling of financial policies.