Do You Know Where Your Strategy Performance Is Coming From?

 | Feb 18, 2022 04:34PM ET

It’s a simple question with a simple answer, but it’s still easy to get sidetracked with misguided analytics. Fortunately, there’s a straightforward solution.

The proper way to decompose returns is by first recognizing that asset allocation usually plays a big role in driving results. A simple example: an equities-only portfolio will likely outperform an equal-weight mix of stocks and bonds in the long run. The main reason, sometimes the only reason: the asset allocation beta in the 100% equities portfolio has a higher risk profile vs. the 50/50 stocks/bond strategy.

If the equities-only portfolio generates an 8% annualized total return vs. 5% for the 50/50 strategy, the additional 3 percentage points in the former can be thought of as asset allocation beta. In other words, by changing the asset allocation (removing bonds and raising exposure to stocks), the equities-only strategy has earned a higher return by piggybacking on the higher performance of a specific asset class. This isn’t alpha since anyone can tap into the results with a forecast-free/analysis-free portfolio change.

So, where does genuine alpha come into play? Let’s run a simple example as an illustration. Imagine you’re considering a 60/40 stock/bond strategy as an investment. A fast-talking money manager comes along and pitches an alternative, with rules as follows:

When the growth-factor slice of the equities market outperforms the value component, the 60% allocation to the overall stock market — SPDR S&P 500 ETF (NYSE:SPY) — is shifted to a growth fund: SPDR Portfolio S&P 500 Growth ETF (NYSE:SPYG). If growth is underperforming, SPY is used for the equity allocation. In either case, a 40% allocation to maintained via iShares Core U.S. Aggregate Bond ETF (NYSE:AGG). (Note: in this toy example I’m using SPYG and SPDR Portfolio S&P 500 Value ETF (NYSE:SPYV) to generate the tactical signal.)

As it turns out, the tactical strategy of shifting between SPY and SPYG outperformed the standard 60/40 mix since 2015. The manager presents the chart below and declares himself a genius. He concludes by noting that his strategy outperformed with a 10.7% annualized total return vs. roughly 9.0% for the 60/40 portfolio. That’s 170 additional basis points of performance, he gleefully notes.