We're not talking about sketchy individuals as you're mentioning. We're talking about banks and institutions that are registered with the National Banking and Trade Commission (ComisiĆ³n Nacional Bancaria y de Valores).
These are major banking institutions that also control and invest for our AFORES (401k) plans. Major corporations such as Cemex, Gruma (Maseca, Mission Foods), Sigma (refrigerated meats and food products) multinationals all invest in banks such as Banorte, BBVA, Santander Scotia, Banamex/CitiBank. These are not fly-by-night operations but banks that support the 15th largest economy in the world.
Anyone who works in these areas has a degree including a Master or two, and highly trained in Finance.