While working as a university teacher, in a marketing class, João Rendeiro created together with a pupil a successful mineral sparkling water brand called Frize, founded as a company in 1994[4] and based in Vila Flor, District of Bragança, that they would later sell to Compal.
[5] However, Rendeiro became nationally renowned and influent after he has founded the Banco Privado Português (BPP) in 1996, a private bank that grew considerably for several years but would collapse in 2008 and went into liquidation.
[6] His private bank followed to bankruptcy for which on 24 July 2009, Paulo Guichard and Salvador Fezas who served as two board of directors committee members of the BPP were suspended and were both joined by Rendeiro with the appointment to a case that involved indicting for falsifying accounts, money laundering and tax crimes.
[8] On 11 February 2013, the three of them were charged by Public Prosecution Service with indictments of intention of deception and fraud in the management of an investment fund.
[9] In a second case, on 15 October 2018, Rendeiro was sentenced by the Judicial Court of the District of Lisbon for committing computer and falsification document forgery.