Momentum Investing

What drives the momentum effect among individual U.S. stocks? In their June 2012 paper entitled “Momentum, Risk, and Underreaction”, Mark Rachwalski and Quan Wen investigate the sources of profits for momentum strategies applied to individual stocks. They measure momentum profitability as average monthly returns to three series of equal-weighted hedge portfolios that each month are long (short) the tenth of stocks with the highest (lowest) returns over the previous three (3-1-1), six (6-1-1), and 12 (12-1-1) months, with a skip-month between ranking intervals and return measurement months to avoid short-term reversal. They test dependence of momentum profitability on five factors: (1) long-term idiosyncratic volatility (IV), the standard deviation of individual stock returns unexplained by the Fama-French model based on daily data from five years ago to six months ago; (2) short-term IV, based on daily data from six months to one week ago; (3) long-term distress risk (corporate default probability) based on daily data from five years ago to six months ago; (4) short-term distress risk based on daily data from six months to one week ago; and, (5) corporate bond beta relative to the BAA yield based on the last two years of daily data. Using daily return data for a broad sample of U.S. stocks, firm accounting information related to default probabilities and corporate bond yield data supporting analysis for 1988 through 2010, they find that: Keep Reading

How do general economic conditions and economy-wide default risk shocks affect corporate bond returns, especially past winners and losers? In the May 2012 draft of their paper entitled “Sources of Momentum in Bonds”, Hwagyun Kim, Arvind Mahajan and Alex Petkevich investigate the relationship between U.S. corporate bond momentum portfolio returns and U.S. aggregate default risk. They measure the momentum effect as average monthly gross returns of overlapping hedge portfolios formed each month by buying (selling) the equally weighted tenth of bonds with the highest (lowest) total cumulative returns over the past six months and holding for six months, with a skip-month between ranking and holding intervals. They measure aggregate default risk as the prior-month yield spread between the Moody’s CCC corporate bond index and the 10-year U.S. Treasury note. They define default risk shocks as deviations from the linear relationships between default risk this month and its values the prior two months. They define high (low) default risk shock conditions as those above (below) the inception-to-date median value of the series. Using price and yield data for all listed U.S. corporate bonds (excluding convertible bonds, asset-backed securities and bonds with very low capitalization) during January 1995 (101 bonds) through December 2010 (2,513 bonds), they find that: Keep Reading

Are there economic conditions that favor stock price momentum investing? In the May 2012 draft of their paper entitled “Momentum and Aggregate Default Risk”, Arvind Mahajan, Alex Petkevich and Ralitsa Petkova investigate the relationship between stock momentum portfolio returns and U.S. aggregate default risk. They measure the momentum effect as average monthly gross returns of overlapping hedge portfolios formed each month by buying (selling) the equally weighted tenth of stocks with the highest (lowest) cumulative returns over the past six months and holding for six months, with a skip-month between ranking and holding intervals. They measure aggregate default risk as the prior-month yield spread between the Moody’s CCC corporate bond index and the 10-year U.S. Treasury note. They define default risk shocks as deviations from the linear relationships between default risk this month and its values the prior two months. They define high (low) default risk shock conditions as those above (below) the inception-to-date median value of the series. Using monthly returns for a very broad sample of AMEX/NYSE/NASDAQ stocks during 1960 through 2009 and monthly default risk spreads since 1954, they find that: Keep Reading

Does momentum investing work when implemented via mutual fund alpha? In his February 2012 paper entitled “Short Term Alpha as a Predictor of Future Mutual Fund Performance” (the National Association of Active Investment Managers’ 2012 Wagner Award runner-up), Michael Hartmann examines a momentum-based approach for selecting outperforming equity mutual funds by investment style. He considers nine equity investment styles: Large Capitalization Growth, Large Capitalization Blend, Large Capitalization Value, Mid Capitalization Growth, Mid Capitalization Blend, Mid Capitalization Value, Small Capitalization Growth, Small Capitalization Blend and Small Capitalization Value. He measures momentum based on fund alpha calculated by linear regression of returns versus those of the S&P 500 Index over the past 20, 40, 60, 80 and 100 calendar days. He then forms non-overlapping portfolios of the three highest-alpha funds (weighted equally) for each style every 45, 70, 95, 120, 135 and 170 calendar days over the entire sample period and compares compound annual return rates for these portfolio series to those for corresponding Russell total return style indexes. Using daily total returns for open-ended mutual funds currently available via the no-transaction mutual fund platform at Charles Schwab & Co. and daily returns for the S&P 500 Index from the end of June 1999 through December 2011, along with sample period compound rates of return for Russell benchmark indexes, he finds that:

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A subscriber asked: “Have you looked at combining sector and asset class momentum models? This strategy would add alternative asset classes plus cash to the nine sectors.” A combined strategy encompasses nine sector exchange-traded funds (ETF) defined by the Select Sector Standard & Poor’s Depository Receipts (SPDR) per “Simple Sector ETF Momentum Strategy” plus the eight ETFs and cash that cut across asset classes per “Simple Asset Class ETF Momentum Strategy” (SACEMS), as follows:

Materials Select Sector SPDR (XLB)
Energy Select Sector SPDR (XLE)
Financial Select Sector SPDR (XLF)
Industrial Select Sector SPDR (XLI)
Technology Select Sector SPDR (XLK)
Consumer Staples Select Sector SPDR (XLP)
Utilities Select Sector SPDR (XLU)
Health Care Select Sector SPDR (XLV)
Consumer Discretionary Select SPDR (XLY)

PowerShares DB Commodity Index Tracking (DBC)
iShares MSCI Emerging Markets Index (EEM)
iShares MSCI EAFE Index (EFA)
SPDR Gold Shares (GLD)
iShares Russell 1000 Index (IWB)
iShares Russell 2000 Index (IWM)
SPDR Dow Jones REIT (RWR)
iShares Barclays 20+ Year Treasury Bond (TLT)
3-month Treasury bills (Cash)

We consider a simple (6-1) strategy that allocates all funds each month to the one sector or asset class ETF/cash with the highest total return over the past six months (effectively pitting the sector winner against the asset class winner). Using monthly dividend-adjusted closing prices for the ETFs over the period July 2002 (limited by data availability for enough asset class ETFs) through April 2012 (118 months), we find that: Keep Reading

A subscriber commented and asked: “You compare style ETF momentum to sector ETF momentum in ‘Doing Momentum with Style (ETFs)’. Can you mix style and sector ETFs to form a combined momentum strategy and compare it with the individual style and sector momentum strategies?” A combined strategy encompasses the nine sector exchange-traded funds (ETF) defined by the Select Sector Standard & Poor’s Depository Receipts (SPDR) plus the six ETFs that cut across market capitalization (large, medium and small) and value versus growth:

Materials Select Sector SPDR (XLB)
Energy Select Sector SPDR (XLE)
Financial Select Sector SPDR (XLF)
Industrial Select Sector SPDR (XLI)
Technology Select Sector SPDR (XLK)
Consumer Staples Select Sector SPDR (XLP)
Utilities Select Sector SPDR (XLU)
Health Care Select Sector SPDR (XLV)
Consumer Discretionary Select SPDR (XLY)

iShares Russell 1000 Value Index (IWD) – large capitalization value stocks.
iShares Russell 1000 Growth Index (IWF) – large capitalization growth stocks.
iShares Russell Midcap Value Index (IWS) – mid-capitalization value stocks.
iShares Russell Midcap Growth Index (IWP) – mid-capitalization growth stocks.
iShares Russell 2000 Value Index (IWN) – small capitalization value stocks.
iShares Russell 2000 Growth Index (IWO) – small capitalization growth stocks.

We consider a simple (6-1) strategy that allocates all funds each month to the one sector or style ETF with the highest total return over the past six months (effectively pitting the sector winner against the style winner). Using monthly dividend-adjusted closing prices for these 15 ETFs over the period August 2001 (limited by data availability for IWS/IWP) through April 2012 (129 months), we find that: Keep Reading

What is the safest way to exploit asset price momentum? In his April 2012 paper entitled “Risk Premia Harvesting Through Momentum”  (the National Association of Active Investment Managers’ 2012 Wagner Award winner with different title), Gary Antonacci investigates systematic capture of upside volatility at the asset class level via a momentum/diversification/absolute return strategy that:

• Exploits momentum via long positions in winners, based on 12-month lagged total returns with no skip month, re-evaluated monthly.
• Maintains diversification by:
  • Using indexes rather than individual securities; and,
  • Holds the equally weighted winners from each the following pairs of competing indexes: gold versus long-term Treasury bonds; U.S. equities versus foreign equities; high yield bonds versus intermediate credit bonds; and equity real estate investment trusts (REIT) versus mortgage REITs.
• Mitigates risk by substituting Treasury bills (T-bills) for each pairwise winner that has not outperformed T-bills during the 12-month ranking interval.

Using monthly total returns for indexes constructed from targeted classes of equities, bonds, REITs and spot gold, along with contemporaneous 90-day Treasury bill yields, during January 1974 (or the earliest available) through December 2011, he finds that: Keep Reading

Stock price momentum strategies sometime crash, greatly detracting from long-term performance. Is there a reliable way to avoid the crashes? In the April 2012 version of their paper entitled “Managing the Risk of Momentum”, Pedro Barroso and Pedro Santa-Clara investigate usefulness of momentum portfolio volatility as a crash protection signal. They construct a momentum portfolio return series based on equal allocations to the risk-free asset (one-month Treasury bill), a value-weighted long side of momentum winners and a value-weighted short side of momentum losers, reformed and rebalanced monthly. They measure momentum for all NYSE/AMEX/NASDAQ stocks based on 11-month lagged returns plus a skip-month, and define winners and losers based on the top and bottom decile cutoffs for NYSE stock momentum. Using daily and monthly momentum portfolio returns and monthly U.S. equity risk factors (market, size, book-to-market) based on stock prices for July 1926 through December 2011, they find that: Keep Reading

Do “new” momentum stocks outperform “old” ones? In the March 2012 version of their paper entitled “Limited Attention, Salience, and Stock Returns” [apparently removed from SSRN, casting doubt on findings], Avanidhar Subrahmanyam, Jason Wei and Hsin-Yi Yu analyze whether stocks newly entering and exiting extreme momentum deciles exhibit unusual future returns because of heightened investor attention. Their benchmark (6-6) strategy consists of conventional overlapping winner-minus-loser momentum portfolios that are long/short those stocks with the highest/lowest returns over the past six months, formed monthly (after a skip-month) and held for six months. They classify a stock as a 6-6 arriver if it is not in any of the five preceding overlapping winner-minus-loser portfolios and a 6-6 dropper if it was in at least one winner-minus-loser portfolio active during the previous five months but is not in any of the active portfolios this month. They also consider arriving and dropping stocks defined relative to ranking intervals of 3, 9 and 12 months and holding intervals of 1, 2, 3, 9 and 12 months. Within portfolios, they weight the winner and loser sides equally and each stock within the winner or loser side equally. Using daily and monthly prices and volumes for NYSE, AMEX and NASDAQ common stocks priced above $5, along with contemporaneous risk factor and robustness test data as available, during 1962 through 2010, they find that: Keep Reading

It is arguable that many exchange-traded fund (ETF) momentum strategy tests derive more from logical/programming simplicity than common portfolio management practices. Does momentum work for portfolios of ETFs when melded with the latter? In his March 2012 paper entitled “Tactical Asset Allocation Using Relative Strength”, John Lewis tests ETF momentum in the context of real-world portfolio practices. He employs a universe of nearly 100 ETFs encompassing U.S. equity sectors and styles, international/global equities, bonds, commodities, real estate and currencies, including some inverse funds. After initial selection of top ETFs, he replaces weakening funds with strong ones as needed based on daily (or weekly) prices rather than at a fixed interval, depending on four parameters: (1) momentum ranking interval; (2) number of ETFs in the portfolio; (3) buy rank threshold; and, (4) sell rank threshold. To test robustness, he conducts multiple trials based on random selection of ETFs above the buy rank threshold. Specifically, he presents seven examples of 100 iterations of 10-ETF portfolios randomly selected from the top 25% of the ETF universe based on momentum ranking intervals of one month to two years, replacing ETFs when they fall out of the top 25%. Portfolios are apparently equally weighted at initial formation. Examples ignore dividends, management fees and trading frictions. Using daily returns for the ETFs from the end of 1999 through the end of 2011 (12 years), he finds that: Keep Reading