After years of research, quant investing pioneer Dimensional Fund Advisors added a new source of return to its investment process, according to a recent article in Institutional Investor.

“Dimensional is adding a new factor based on the behavior of companies with high levels of investment.” The firm’s head of research, Savina Rizova and co-author Namiko Saito published new research that examined the behavior of stocks with high investment—as measured by asset growth—and “whether it could be used to improve returns for investors.” The authors found that companies with lower cash flows and higher investment levels—those that pour money into research and development and other profit-boosting initiatives—will have lower expected returns in the future. They found that the relationship held across multiple markets and sectors.

But the important part of the findings was that the negative relationship between investment and stock returns was driven by the underperformance of small firms with high investment, the article reports. This was significant, according to Rizova, because it informed how to capture the source of return: “If you naively say the theory implies a negative relationship, you should see it in large and small stocks. Then you can apply it by using underweights and overweights. But we observed in large caps, that it was a weak relationship.” The paper suggests that the weak relationship may be due to the low level of asset dispersion among large-cap firms relative to small-cap firms.

Dimensional will quantify the investment factor using asset growth as a proxy. Rizova says that firms can raise capital to invest with equity financing, debt financing and retained earnings, and that asset growth measures a combination of all three—so, the firm focuses on asset growth as a measure of investment.