What is "dual-beta"

In investing, dual-beta is a concept that states that a regular, market beta can be divided into downside beta and upside beta. Thus, dual stands for two betas, upside and downside. The fundamental principle behind dual-beta is that upside and downside betas are not the same. This is in contrast to what the Capital Asset Pricing Model assumes, which is that upside and downside betas are identical. Moreover, Fama and French (1992) demonstrated that beta is an imperfect measure of investment risk.