In item B 1963, william sharpe proposed a single-factor model that can simplify covariance matrix estimation, which greatly promoted the practical application of portfolio theory. Item C, CAPM)； proposed by Sharp, Lint and Mohsen in 1960s); At 1964, 1965 and1966 respectively; Item D, 1976, stephen ross puts forward an alternative capital asset pricing model, namely the arbitrage pricing theory model (APT model), in view of the unverifiable defect of CAPM model.