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 ...