Board leadership structure and diversity over CEO time in office: A test of the evolutionary perspective on Italian firms

•We combine agency and stewardship theories in a unified model of CEO-board relation.•Agency and stewardship theories applies to different stages of CEO tenure.•CEO duality enhances innovation early in CEO tenure, harms it later in tenure.•Board resources foster innovation to a greater extent, as CEO tenure progresses.•Stewardship and agency theories are complementary along the CEO tenure cycle.

An evolutionary perspective on CEO-board relations suggests that CEO objectives and interests change over time, and that board roles should shift accordingly, from CEO leadership development during the early stages of CEO time in office toward monitoring during the latest stages. This study examines how two board characteristics, board leadership structure and board diversity, shape innovation investment among Italian firms. Empirical results support the hypothesized effects, suggesting that the board’s effects are contingent upon CEO time in office.