Gary G. Schlarbaum, The Investment Performance of the Common Stock Portfolios of Property-Liability Insurance Companies, The Journal of Financial and Quantitative Analysis, Vol. 9, No. 1 (Jan., 1974), pp. 89-106

In an efficient capital market, prices fully reflect available information and adjust to new information in a rapid and unbiased fashion. As a result, prices provide unbiased estimates of the underlying values. No known trading rule or security selection strategy which uses only publicly available information would provide an investor with the ability to earn, on average, positive “abnormal” returns in a market that is efficient in the semi-strong sense. Thus, a finding that common stocks selected, using a readily available, widely disseminated set of rules which requires only publicly available information for decision-making purposes, earn, on average, positive abnormal returns represents strong contradictory evidence regarding the semi-strong form of the efficient markets hypothesis.

This paper develops a credit-analysis model encompassing the accuracy of analytical methods, quality of applicants, cost of acquisition and analysis, profit from good loans, and losses from bad loans. Information generally available to the lending institution and subjective estimates can then be used to select from among alternative credit-granting systems the system with the greatest expected net present value. Each institution is thus able to find the credit granting system most appropriate for its particular market and analytical abilities.The model's profit maximizing objective and broad scope make it useful for setting credit department standards of performance. Costs can be compared with theoretical values of performance computed from loss rates, acceptance rates, and market information. The conditional probabilities, the chances of making the correct decision, can also be estimated for use in comparing methods of analysis or individual analysts. Unlike the loss rate, the conditional probability is an independent, unbiased measure of a method's accuracy.The example presented dealt with consumer installment loans, but the formulation is applicable to direct lending of any type. It provides the means for comparing loans with differing initial costs as well as widely varying risk classes and maturities. Financial institutions making direct loans add substantial values to capital supplied by the money and capital markets. The model is a theoretical formulation of the relationship between the cost and output of credit analysis.

The operation and characteristics of the American securities markets have long been major preoccupations of financial research, especially during the last decade. Particular attention has been devoted to the question of whether there exist investment strategies, or investing entities, capable of producing consistently superior investment performance. The general consensus to date is that few, if any, such success stories are observable. Examinations of the value of professional investment research and counsel ([7] [8] [9] [24]), of the payoff from technical trading rules ([11] [13] [18] [20] [26] [34]), and of the investment results of institutional money management ([15] [29] [25] [28]) have, in almost every instance, provided little indication of performance better than that attainable from a simple passive strategy of buying and holding a randomly selected, well-diversified portfolio of securities, after appropriate adjustments for portfolio risk levels are taken into account. The intensive competition in, and rapid information-digesting properties of, the capital market environment have been cited as explanations ([2] [5] [12]).

This article explores the price behavior of a sample of corporate securities in which trading was temporarily suspended by the SEC. Suspensions are found to coincide with substantial devaluations of the suspended securities. Further, significant and prolonged negative abnormal returns are observed in the postsuspension period, an apparent violation of semistrong form market efficiency.