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The asymmetry test. High up-capture + low down-capture = the dream.
Up-capture is the percentage of the benchmark's gains a portfolio captured during up months; down-capture is the percentage of the benchmark's losses it captured during down months. The dream profile is high up-capture and low down-capture — for example 90% up-capture and 60% down-capture is asymmetric outperformance.
Up = Rp/Rm (when Rm > 0) · Down = Rp/Rm (when Rm < 0)Up-Capture = Rp / Rm (when Rm > 0)
Down-Capture = Rp / Rm (when Rm < 0)You split the historical record into up-months for the benchmark and down-months. Compute compound returns for the portfolio in each set. The up-capture is the ratio in up months; the down-capture is the ratio in down months.
Capture ratios reveal asymmetric performance that single-number metrics hide. A defensive equity strategy might have beta of 1.0 (looks fully exposed) but capture 90% of upside and only 60% of downside — far better than its raw beta suggests.
The best long-term performers tend to have up-capture in the 90–105% range and down-capture in the 60–85% range. That is the holy grail: stay close to the market in good times, dodge the worst of the bad times.
Over 5 years, the S&P 500 compounded +12% in its up-months only and −8% in its down-months only. Your portfolio compounded +10% in those up-months and −5% in those down-months.
Up-Capture = 10% / 12% = 83%
Down-Capture = −5% / −8% = 63%
Excellent asymmetry — you participated in 83% of the upside but ate only 63% of the downside. The product (0.83/0.63 = 1.32) is what makes this a superior strategy long-term.
The "good" target depends on strategy. Defensive equity should aim for low down-capture; growth equity acknowledges higher down-capture but demands more upside. The ratio Up/Down is the headline summary number.
High up-capture (above 90%) and low down-capture (below 75%). Up/Down ratio above 1.2 over multi-year periods is exceptional.
Asymmetric capture only helps if both numbers are reasonable. Down-capture of 95% with up-capture of 80% still loses, even though down is "lower" than up.
Beta is a single number assuming linear sensitivity. Capture ratios separate up-month and down-month sensitivity — capturing asymmetric beta.
Yes — against the S&P 500 and other benchmarks in the timing section of the metrics panel.
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