We find a significant negative association between cost of equity and audit committee directors' simultaneous service on multiple audit committees (ACNUM). However, this association is not linear as we find that cost of equity begins to increase when ACNUM is 1.50 for non-retired directors compared to 3.50 for retired directors. Further analyses reveal the negative association is more pronounced when a firm's information environment is strong and widely used firm-level measures of multiple directorships are not related to cost of equity. The evidence we present is consistent with the notion that investors positively perceive audit committee directors' service on multiple audit committees, but only to the extent such service does not undermine directors' ability to effectively discharge their governance responsibilities. Our study informs policy makers, boards and nominating committees, and advances the literature on multiple directorships, audit committees, and cost of equity.