Two former Deutsche Bank AG traders were found guilty of trying to rig a key lending benchmark that was considered one of the most important barometers of the world’s financial health.

Matthew Connolly, who led Deutsche Bank’s pool trading desk in New York, and Gavin Campbell Black, a former derivatives trader who worked on the bank’s London desk, were convicted Wednesday of conspiracy and wire fraud charges following a monthlong trial in Manhattan federal court.

Sentencing...