Most business valuers depend on forecasted cash flows to determine whether the founder or owners of a business are increasing value, and some will sense that managing directors or CEOs who have held the job for a long time tend to have less ambitious growth plans.

If you’re valuing a business with a CEO who has been in that job for 20 years, is that a positive or a negative? A new research paper confirms this assumption, reporting that there is a real bell curve relationship between CEO tenure and firm value. The top of the bell curve is in Year 14, the paper finds.

The authors, Francois Brochet (Boston University), Peter Limbach (University of Bielefeld Centre for Financial Research), Markus Schmid (University of St. Gallen), and Meik Scholz-Daneshgari (Karlsruhe Institute of Technology), further discovered that even the most financially successful CEOs “may be associated with declining firm value” toward the end of their long careers. “CEO Tenure and Firm Value” was first presented in 2015 but was released with current updates last week.