PT  - JOURNAL ARTICLE
AU  - Martin L Leibowitz
AU  - Anthony Bova
TI  - Diversification Performance and Stress-Betas
AID  - 10.3905/JPM.2009.35.3.041
DP  - 2009 Apr 30
TA  - The Journal of Portfolio Management
PG  - 41--47
VI  - 35
IP  - 3
4099  - https://pm-research.com/content/35/3/41.short
4100  - https://pm-research.com/content/35/3/41.full
AB  - In earlier research, the authors found that, on both a theoretical and historical basis, the typical diversified fund exhibits volatility characteristics that are strikingly similar to a traditional 60/40 allocation and, in severe market declines, should theoretically underperform the 60/40 portfolio. This latter and surprising result is due to the stress-beta effect that derives from diversification because the multiple asset classes are more vulnerable to correlation tightening than the two-asset 60/40 allocation. The year 2008 provided an (unwelcome) opportunity for the authors to test this stress effect. They found that in 2008 the diversified portfolio's correlation-based beta was, in fact, much higher than in normal times and that 2008 was the first period in which the diversified portfolio performed materially worse than the 60/40 portfolio. Thus, the typical model of institutional diversification should be viewed not as reducing risk in the short-term, but rather as a source of longer-term benefits in the form of greater return accumulation and wider divergence of outcomes.TOPICS: Portfolio construction, accounting and ratio analysis, financial crises and financial market history