Fast Factor Momentum?

Is U.S. equity factor return momentum broader and stronger for a short momentum measurement lookback interval than for a long one? In their July 2025 paper entitled “Revisiting Factor Momentum: A One-month Lag Perspective”, Mikael Rönkkö and Joonas Holmi compare U.S. equity factor momentum for 1-month and 12-month lookback intervals. They consider individual factor time series momentum and a momentum portfolio that is each month long or short factors based on the signs of respective factor returns the previous month or year. Their benchmark strategy takes long (short) positions in factors with positive (negative) historical average returns. Using monthly gross returns for 138 non-momentum, value-weighted U.S. equity factors with at least 10 years of data as available during July 1963 through December 2024, they find that: (more…)