Moving Average Timing of Stock Fundamental Ratios

Can investors time premiums associated with widely used stock/firm fundamental ratios? In their September 2018 paper entitled “It Takes Two to Tango: Fundamental Timing in Stock Market”, Fuwei Jiang, Xinlin Qi, Guohao Tang and Nan Huang use a simple moving average (SMA) trend indicator to time premiums associated with four fundamental stock/firm ratios: book-to-market (BM), earnings-to-price (EP), gross profitability (GP), and return-on-assets (ROA). In calculating these ratios, they lag accounting variables by six months to avoid look-ahead bias. For each ratio, they:

• At the end of each June, rank stocks into tenths (deciles).
• Each day, calculate value-weighted average returns for the deciles with the highest (highest BM, EP, GP, ROA) and lowest (lowest BM, EP, GP, ROA) expected returns and maintain price indexes for these two deciles.
• Each day, hold a long (short) position in the decile with highest (lowest) expected returns only when the decile price index is above (below) its 20-day SMA, indicating an upward (downward) trend. When not holding a decile, hold Treasury bills.

As benchmarks, they each year buy and hold four portfolios that are each long (short) the value-weighted deciles with the highest (lowest) expected returns for one of the fundamental ratios. While focusing on a 20-day SMA, for robustness they also test SMAs of 10, 50, 100 and 200 trading days. While focusing on value weighting, they also look at equal weighting. They run tests on both non-financial Chinese A-share stocks and non-financial U.S. common stocks. Using annual groomed fundamentals data and daily returns for Chinese stocks during January 2001-December 2017 and for U.S. stocks during July 1970-December 2017, and contemporaneous Treasury bill yields, they find that:

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