Another week, and more concerns about the Italian banking system. A reminder: Monte dei Paschi di Siena (MPS), the world’s oldest bank founded in 1472, has an estimated $55 billion in bad loans on its books and is expected to be among the worst performers in European banking stress tests next week. Shares in the 544-year old bank, the third-largest in Italy by assets, are trading at 8% of book value. Italian officials have been pushing for government assistance to help bail out the bank, but E.U. banking rules require private investors to be wiped out first before there is public assistance.