The Monetary Authority of Singapore (MAS) said its investigations found numerous instances where payments were made to supervisors over sales of investment products and life policies, violating its regulations.
Those reprimanded were AIA Financial Advisers (AIA FA) Private Limited, Prudential Assurance Company Singapore, Aviva Ltd and Aviva Financial Advisers Pte Ltd.
The MAS has dealt firmly with these financial institutions "to send a clear message to the industry on the importance of upholding high ethical standards," Ho Hern Shin, MAS deputy managing director, financial supervision, said in a statement.
In response to Reuters' queries, an Aviva Singapore spokesperson said: "we have strengthened our controls to prevent the recurrence of such issues, and these are being validated by an independent external auditor."
Prudential said it would work closely with the MAS to enhance its controls related to the issues raised.
AIA FA said it would work closely with MAS for the remediation actions required, adding it was fully committed to protecting its customers' interests and that none had been affected.
MAS in a response to Reuters questions said its reprimand "registers MAS' serious concerns regarding the misconduct" and that financial institutions and individuals "are required to remediate issues promptly."
(Reporting by Chen Lin; Editing by Martin Petty)