ON THE THEORETICAL RELATIONSHIP BETWEEN BUSINESS RISK AND SYSTEMATIC RISK
推导了经营风险与系统风险之间的理论关系，允许价格、可变成本和需求同时随机，利用随机变量乘积的协方差，为理解杠杆系统风险的时间不稳定性提供了理论来源。
This article develops a theoretical relationship between systematic risk and business risk. It is an area that has not been substantially developed in the literature. Rubinstein (1973) and Lev (1974) both developed theoretical models of systematic risk allowing for stochastic demand. A model is derived that allows for prices, variable costs and demand to be simultaneously stochastic, utilizing the covariance of the product of random variables. The temporal stationarity of unlevered systematic risk is dependent upon the temporal stationarity of the theoretical structure derived. Insight is gained as to a potential source of the empirically observed temporal instability of levered systematic risk.