Milan, February 9 - Italy's third-biggest bank Monte dei Paschi di Siena (MPS) posted a 3.5 billion euro loss in 2017, up from 3.2 billion in 2016, the bank said Friday. Adjustments worth some 5.4 billion euros were put on the balance sheet in 2017, MPS said. In the last quarter of last year it posted a loss of 502 million euros due to the sale of its NPL platform. Economy Minister Pier Carlo Padoan said the bank, which has been through an expensive turnaround, "will become ever more vital". Its management was "working flat out," he added.