This study examines voluntary disclosure differences between single business segment firms and multiple business segment firms. Using management earnings guidance data this paper provides evidence that focused firms are less likely to provide an earnings forecast after controlling for typical determinants of forecast issuance, including various controls for competitive pressures and firm complexity. These results are consistent with higher proprietary costs of disclosure for focused firms potentially stemming from their disclosures being at a finer level of detail. Tests showing that disclosure ranking is not related to excess value are inconsistent with the alternative explanation that diversified firms are more likely to disclose in an attempt to mitigate their intrinsic opacity and therefore reap greater benefits of disclosure.