What we do know is that Vatican Bank, officially titled the Institute for the Works of Religion, manages €5.9bn ($7.3bn, £4.64bn) of assets on behalf of its 17,400 customers. And it manages €700m of equity which it owns. Another titbit to emerge is that it keeps gold reserves worth over $20m with the US Federal Reserve.
The bank has been caught up in a number of scandals in the past, including the funding of priests caught up in sex abuse allegations and of money laundering for the Mafia and former Nazis.
This is why there are moves within parts of the church to make it more like a normal bank and open up its accounts for greater scrutiny. Protections for religious organisations mean it does not currently face the same transparency obligations as other financial institutions.