The Monte dei Paschi grows more ugly (for any English person so very familiarly ugly) by the day. And it is its recent days, not its 500 year history, that matters now; the last half century, not the last half millennium. Since the Second world war the Monte dei Paschi has been wholly in the control of the hard Left currently masquerading as the Democratic Party.
Undoubtedly other institutional players have benefitted from the iron grasp of the Left on central Italy, a grip enabled and reinforced by control of the Bank. No entity exists in a vacuum but survives and grows by exchange: exchange of favours, exchange of secrets, exchange of personnel, exchange, above all, of guilt. So it is fairly easy now for the Left to do the pointy finger at others - Church, political parties or factions within them, individuals - united in guilt.
Still there remains the reality: the post-Second world war Monte dei Paschi has been the cash cow and creature of the Left (centrally important after the collapse of realised socialism and the end of the enormous subsidies paid from the USSR); this is the Treasury of the state within the state.
The Bank has been under scrutiny by the Bank of Italy since at least 2008, when Mario Draghi as Governor of the Bank of Italy, was cleaning up the pale copies of the Siena model repeated in local governments and petty financial institutions all over Italy. So important (and self-important) was Siena that it simply lied when asked for information. And continued to buy complicity, not from those whose duty it was to secure financial affairs, but from those who could profit from remaining silent.
Effectively, with the requirement to accept government bail-out, the entire Siena structure is being silently nationalised. But dealing with the funding of democratically unpopular factions within coalition parties, that succeed in imposing themselves upon entire political movements, may be in safe hands only temporarily. If Bersani and his apparatchiks manage to impose themselves upon us at the end of February they will have control of the Italian Treasury - and Siena will become irrelevant.