April 15 (Bloomberg) — Brazilian chief executive officers are fighting to keep their salaries secret.

Companies from Embraer SA to Itau Unibanco Holding SA to Vale SA, all with American depositary receipts, don't disclose compensation for top officials, contrary to international norms in countries like the U.S. and U.K. Four years after securities regulator CVM ordered release of expanded pay details, more than a third of Brazil's most-traded companies are refusing to do so as a court case against the decision plays out.

Shareholders say the information ensures CEOs don't overpay themselves to the detriment of investors, while corporations say the rule violates managers' privacy and puts them at risk for kidnapping. They cite the case of Abilio Diniz, who was held hostage for several days in 1989 when he was an executive at supermarket chain Cia. Brasileira de Distribuicao Grupo Pao de Acucar, and the escape of three children of billionaire Jorge Paulo Lemann from an attempted abduction in 1999.