Long-only Factor Investing with Little or No Trading

What is the right balance between seeking alpha and avoiding taxes? In their August 2023 paper entitled “Alpha Now, Taxes Later: Tax-Efficient Long-Only Factor Investing”, Yin Chen and Roni Israelov assess trade-offs between rebalancing benefits and tax avoidance from overlapping 10-year backtests of long-only momentum, value, quality and safety factor stock portfolios. They measure momentum as cumulative return from 12 months ago to one month ago, value as book-to-market ratio, quality as operating profitability and safety as winsorized market betas. All portfolios start with the equal-weighted top fifth (300 stocks) as ranked by the factor metric. After initial formation, they consider five monthly portfolio management rules:

1. Fully Rebalanced, each month selling stocks that drop out of the top fifth and buying stocks that enter the top fifth, but not adjusting weights of stocks that remain in the portfolio.
2. Buy-and-Hold (no rebalancing over the 10-year portfolio life).
3. Sell Losers at Losses, each month selling stocks that have migrated to the bottom fifth if they have capital losses.
4. Tax Loss Harvesting, each month selling stocks with more than 5% unrealized losses and not buying them back until at least 30 days later.
5. Tax Loss Harvesting and Sell Losers, selling stocks that have migrated to the bottom fifth even if they have unrealized capital gains so long as the aggregate realized capital gain is zero.

They form the first portfolio for each factor in June 1964 and initiate new portfolios every six months until January 2012, such that the last portfolio is held through December 2021. They focus on 1-factor (market) alpha, averaged across overlapping portfolios, as the key performance metric. To calculate net performance, they assume 0.08% 1-way trading frictions, 23.8% dividend tax rate and 23.8% (40.8%) long-term (short-term) capital gain tax rate. Based on initial findings, they repeat all tests on composite portfolios of value, quality and safety factors constructed by ranking stocks on individual factors and investing equally in the fifth of stocks with the highest combined rankings. Using data as specified for the 1,500 U.S. stocks with the largest market capitalizations at the end of each prior year during 1964 to 2021, they find that:

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