Concentrated Portfolios of Momentum Stocks

Abstract

There exists abundant academic literature showing that momentum, i.e. a positive correlation between initial ranking of stocks by their past returns and subsequent returns, is pervasive across different markets and time periods. Although recent criticism speculates on the disappearing of momentum returns, as-set managers have launched strategies to harvest the risk premia in form of well diversified equities funds based. In this research paper I delve deeper into the topic of the construction of concentrat-ed portfolios with less than 50 stocks. Based on monthly data for the US market universe I first investigate the consistency of momentum returns over the latest 20 years (1999-2019) with deciles analysis and then study the characteristics both of unconstrained and sector neutral concentrated portfolios. The empirical results show that momentum in the last decade (2010-2019), measured as the performance of a zero investment portfolio (long winners and short losers), is present but with minor intensity compared to the previous decade and that on the same period the top decile “long only” portfolio, built with previous winners’ stocks, still keeps beating the markets index with better Sharpe and Sortino ratios. The results on concentrated portfolios, in particular portfolios with less than 10 stocks, show clear dependency on the given universe constituents, to make the analysis less dependent on particular universe constituents I propose to run the momentum strategy on 1000 random subsampled stocks universes and show empirically that the relation between the number of stocks in the portfolios and the corresponding performances is statistically significant monotonic (the less stocks the more performance). Finally, I report that a sector neutral portfolio, i.e. a portfolio with the same number of stocks for each industrial sector, shows superior risk return characteristics than unconstrained ones. In the last 20 years a long only portfolio based on overlapping sector neutral sub-portfolios with 10 stocks each, gained an annualized return of 11.3% with a Sharpe ratio of 0.59, compared to a 6.00% and 0.24 for the MSCI USA and a 8.5% and 0.38 for the equal weighted benchmark.