Thursday, June 12, 2008

Beta and Sectors

I meant to post something about the interest rate environment and tactical asset allocation, but I haven't gotten around to it since the results aren't that spectacular. Still kind of interesting. Anyway, I've been reading Eric Falkenstein lately over at the Falkenblog and his website DefProb.

One point that he makes is that historically buying low Beta stocks has better returns than buying high Beta stocks (though there are periods of significant underperformance such as the internet bubble). I found this result interesting (risk is inversely related to returns, how could that not be interesting?) and so decided to look into a similar strategy using sectors.

I used weekly dividend adjusted data of the 9 Sector Spiders since they began at the end of '98 along with SPY. I calculated Beta vs. SPY using at least a year's worth of data and no more than 5 years worth of data. At the start of every year I ranked the Sectors on the basis of Beta and formed a high Beta and low Beta portfolio with three Sectors each. I also calculated a portfolio investing equally in each Spider to serve as comparison (SPY is market-weighted).

Over this period (from Jan. 2000 to the end of last week), the equal-weight portfolio return 2.4% annually (15.7% std), the high beta portfolio returned -.14% (20.7 std), and the low beta portfolio returned 4.3% (14.3% std).

I then calculated the 40 week (200 day) moving average and considered a signal at the beginning of the month good through the end of the month (since that is how the 10 month TAA works and I wanted it to be somewhat comparable). The results are reported below:
(After accidentally inflating the returns of the high portfolio) The results indicate that the low Beta portfolio outperforms when the market is above the 40 week moving average and slightly outperforms when the market is below the 40 week moving average which confirms the argument that Mr. Falkenstein had made (note that the Sharpe ratio is higher for the high than the low in the below 40 week, I think that the Sharpe ratio is an incorrect method of comparison when returns are below 0). That doesn't change the fact that investing when below the 200 day moving average is very risky.

CFO advisory posted yesterday regarding the sector momentum strategy (which I have covered before on this site) and noted that a significant portion of the return has been due to XLE. The low Beta portfolio included XLE from 2000 to the beginning of 2007; however, from 2007 until recently XLE return 35% annualized compared to 11% from 2000 to 2007. So I would argue that the performance of the low Beta portfolio doesn't suffer from the XLE criticism (note that I really agree with it anyhow).

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