MILAN, May 6 (Reuters) - The main shareholder in bailed-out Italian lender Banca Monte dei Paschi di Siena has cut its valuation of the bank to a quarter of what it was two years ago in the wake of a scandal over risky derivatives deals.
Italy's third biggest bank by number of branches was forced to take a state bailout of 4.1 billion euros in February to plug a capital shortfall exacerbated by the derivatives deals, which are at the centre of a criminal probe over alleged fraud.
The Monte dei Paschi foundation said on Monday it had written down its 33.5 percent stake in the bank by another 460 million euros after the scandals, to 952 million euros, following a massive 3.5 billion euro writedown in 2011 that applied to a slightly larger stake.
The foundation, a non-profit entity with strong ties to local politicians in the bank's base in Siena, ended 2012 with a loss of 194 million euros ($254 million).
The book value of the stake is now 0.24 euros per share from 0.36 euros previously. The stock traded at 0.21 euros by 1121 GMT.
The foundation has a further 0.7 percent stake in the bank that it has put up for sale to help repay debt. ($1 = 0.7624 euros) (Reporting by Silvia Aloisi and Stefano Bernabei; editing by Patrick Graham)