Letters exchanged between the Securities and Exchange Commission and an important study group in the European Union are offering new hints to companies trying to bridge a trans-Atlantic regulatory spat over whistleblower hotlines.

The correspondence—swapped between Ethiopis Tafara at the SEC Office of International Affairs and the EU Article 29 Data Protection Working Party—addresses the year-long tensions between American regulators who want companies to have whistleblower hotlines as mandated by the Sarbanes-Oxley Act, and EU officials who deeply frown on the idea of one citizen reporting another to the authorities anonymously. Both sides have struggled to settle their differences over the issue, while U.S.-listed multinational companies twist in limbo.