The Canadian Investment Regulatory Organization (CIRO) is responsible for overseeing trading and market-related activities of participants on Canadian equity marketplaces. CIRO conducts surveillance to ensure compliance with rules, regulations, and fair market practices.

Other options:

OBSI (Ombudsman for Banking Services and Investments) : Handles disputes between financial institutions and their clients but does not conduct trading surveillance.

OSFI (Office of the Superintendent of Financial Institutions) : Regulates and supervises federally regulated financial institutions, focusing on their solvency.

CSA (Canadian Securities Administrators) : Coordinates securities regulation across Canada but does not directly monitor trading activities.