Journal of Finance
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Опубликовано на портале: 15-11-2004Phoebus J. Dhrymes, Irwin Friend, N. Bulent Gultekin Journal of Finance. 1984. Vol. 39. No. 2. P. 323-346.
This paper demonstrates that the Roll and Ross (RR) and other previously published tests of the APT are subject to several basic limitations. There is a general nonequivalence of factor analyzing small groups of securities and factor analyzing a group of securities sufficiently large for the APT model to hold. It is found that as one increases the number of securities, the number of "factors" determined increases. This increase in the number of "factors" with larger groups of securities cannot readily be explained by a distinction between "priced" and "nonpriced" risk factors as it is impermissible to carry out tests on whether a given "risk factor is priced" using factor analytic procedures.
Опубликовано на портале: 06-10-2004Robert Geske, Herbert E. Johnson Journal of Finance. 1984. Vol. 39. No. 5. P. 1511-1524.
An analytic solution to the American put problem is derived herein. The hedge ratio and other derivatives of the solution are presented. The formula derived implies an exact duplicating portfolio for the American put consisting of discount bonds and stock sold short. The formula is extended to consider put options on stocks paying cash dividends. A polynomial expression is developed for evaluating these formulae. Values and hedge ratios for puts on both dividend and nondividend paying stocks are calculated, tabulated, and compared with values derived by numerical integration and binomial approximation. As with European options, evaluating an analytic formula is more efficient than approximating the stock price process or the partial differential equation by binomial or finite difference methods. Finally, applications of this American put solution are discussed.