Upside beta

In investing, upside beta is the element of traditional beta that investors do not typically associate with the true meaning of risk.{{cite web|title=The Entrepreneur's Cost of Capital: Incorporating Downside Risk in the Buildup Method|url=http://www.macrorisk.com/wp-content/uploads/2013/04/MRA-WP-2013-e.pdf|accessdate=26 June 2013|author=James Chong |author2=Yanbo Jin |author3=G. Michael Phillips |page=2|date=April 29, 2013}} It is defined to be the scaled amount by which an asset tends to move compared to a benchmark, calculated only on days when the benchmark's return is positive.

Formula

Upside beta measures this upside risk. Defining r_i and r_m as the excess returns to security i and market m, u_m as the average market excess return, and Cov and Var as the covariance and variance operators, the CAPM can be modified to incorporate upside (or downside) beta as follows.{{cite journal|last=Bawa|first=V.|author2=Lindenberg, E.|title=Capital market equilibrium in a mean-lower partial moment framework|journal=Journal of Financial Economics|year=1977|volume=5|issue=2|pages=189–200|doi=10.1016/0304-405x(77)90017-4}}

:\beta^+=\frac{\operatorname{Cov}(r_i,r_m \mid r_m>u_m)}{\operatorname{Var}(r_m \mid r_m>u_m)},

with downside beta \beta^- defined with the inequality directions reversed. Therefore, \beta^- and \beta^+ can be estimated with a regression of excess return of security i on excess return of the market, conditional on excess market return being below the mean (downside beta) and above the mean (upside beta)."{{cite journal|last=Bawa|first=V.|author2=Lindenberg, E. |title=Capital market equilibrium in a mean-lower partial moment framework|journal=Journal of Financial Economics|year=1977|volume=5|issue=2|pages=189–200|doi=10.1016/0304-405x(77)90017-4}} Upside beta is calculated using asset returns only on those days when the benchmark returns are positive. Upside beta and downside beta are also differentiated in the dual-beta model.

See also

References

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