ABSTRACT We report evidence on the determinants of whether the relationship between a firm and its Chief Executive Officer (CEO) is governed by an explicit (written) or an implicit agreement. We find that fewer than half of the CEOs of S&P 500 firms have comprehensive explicit employment agreements. Consistent with contracting theory, explicit agreements are more likely to be observed and are likely to have a longer duration in situations in which the sustainability of the relationship is less certain and where the expected loss to the CEO is greater if the firm fails to honor the agreement.

We document that backfilling in the ExecuComp database introduces a data-conditioning bias that can affect inferences and make replicating previous work difficult. Although backfilling can be advantageous due to greater data coverage, if not addressed, the oversampling of firms with strong managerial incentives and higher subsequent returns leads to a significant upward bias in abnormal compensation, pay-for-performance sensitivity, and the magnitudes of several previously established relations. The bias also can lead to one misinterpreting the appropriate functional form of a relation and whether the data support one compensation theory over another. We offer methods to address this issue. Received May 12, 2014; editorial decision May 10, 2016 by Editor David Hirshleifer.