McKinsey, one of the world’s most influential consulting firms, has built up a secretive $5bn internal investment arm that manages the fortunes of its past and present partners, raising questions over possible conflicts of interest. Known as McKinsey Investment Office Partners, it is overseen by a 12-strong board of the consultant’s most senior partners and advisers, according to documents seen by the Financial Times. The firm’s partners on the board — which include the heads of the Americas, energy, investment banking, and private equity divisions — do not disclose their work at the fund in their corporate biographies, and they are not named on MIO’s website. The existence, size and investments of the highly profitable internal trading fund, which was set up three decades ago, have until now remained largely unknown outside a circle of former and current McKinsey insiders. Ex-partners at the prestigious firm have gone on to run some of the world’s largest companies or have taken up important government positions.“ Given the size of the internal investment fund, it raises the question of whether there’s a conflict of interest here between McKinsey’s investment strategy and its clients’ needs,” said Fiona Czerniawska, director of Source Global Research, an authority on the consulting industry.