I evaluate the forced CEO turnover rate and quantify effects on shareholder value by estimating a dynamic model. The model features learning about CEO ability and costly turnover. To fit the observed forced turnover rate, the model needs the average board of directors to behave as if replacing the CEO costs shareholders at least $200million. This cost mainly reflects CEO entrenchment rather than a real cost to share-holders. The model predicts that shareholder value would rise 3% if we eliminated this perceived turnover cost, all else equal. The model also helps explain the relation between CEO firings, tenure, and profitability.