Agricultural Bank of China’s head Zhang Yun resigned last Friday for personal reasons, but respected business magazine Caixin then said the resignation was linked to an anti-corruption case investigating another bank official.

Zhang was demoted within the Communist Party and put on two years of probation following the investigation by the Central Commission for Discipline Inspection, said Caixin, noting that it’s not clear if investigators found proof of wrongdoing.

The anti-corruption investigation into China’s finance industry has picked up steam over the past month. Yesterday the biggest state-owned bank, ICBC, said 137 staff had been disciplined in a graft investigation. That followed similar actions at the country’s biggest state-owned investment bank, Citic Group, and China Construction Bank, the second biggest state-owned lender. ICBC, CCB and Agricultural Bank are all bigger than the U.S.’s biggest bank, JPMorgan Chase & Co. (JPM) by assets.

Close observers of the Communist Party say the recent focus on corruption within the finance system is partly a legitimate insider-trading investigation, but also a political campaign to break up political cliques in the country’s biggest state-owned enterprises.