Stress tests by the European Banking Authority found that BMPS would have the greatest difficulty out of 51 of Europe's banks covering its loans.
Stricken Italian lender Banca Monte dei Paschi di Siena looked set to win an 11th hour reprieve Friday night when it announced it had secured underwriters to back a turnaround – just at the point when Europe's banking authority placed it on the danger list of the region's financial industry.
Stress tests by the European Banking Authority found that BMPS, the world's oldest bank, would have the greatest difficulty out of 51 of Europe's top banks covering its toxic loans between now and 2018 in adverse economic conditions.
The EBA unveiled that the Italian lender's fully-loaded common equity tier 1 capital (CET1) ratio – a key measure of a bank's ability to withstand shocks - would fall into negative territory, -2.23 percent, if faced with an adverse economic scenario in 2018; a swing of 14.23 percent from what is expected to be the baseline scenario.
The EBA put the bank's balance sheets under a severe economic stress which included a 7.1 drop in gross domestic product, a drop-off in interest income and a collapse in the real estate market . However, the EBA did not test for a "Brexit" of the U.K. from the European Union or a prolonged period of negative interest rates.
BMPS was a long way ahead of the banks with the nearest worrying transitional CET1 ratio. They are:
•Raiffeisen Landesbanken (Austria) 6.14 percent
•Banco Popular (Spain)7.01 percent
•Unicredit (Italy) 7.12 percent
•Barclays (U.K.) 7.30 percent
•Allied Irish Banks (Ireland) 7.39 percent
•Commerzbank (Germany) 7.42 percent
•Bank of Ireland 7.69 percent
•Deutsche Bank (Germany) 7.8 percent
•Societe Generale (France)8.03 percent
Late Friday, BMPS announced in a statement that it had secured underwriters to back a turnaround plan involving the sale of 9.2 billion euros ($10.3 billion) in bad loans and a 5 billion euros capital increase.
Italy's third largest lender has repeatedly received bailouts in recent years. Shares in BMPS have been particularly volatile in the past few months and is down nearly 77 percent since the start of the year.
Italy's banks have been hit hard by the level of its toxic loans. These were not unpaid home loans but small and mid-undercapitalized companies that make up the bulk of the country's economy
"Whilst we recognize the extensive capital-raising done so far, this is not a clean bill of health," Andrea Enria, EBA Chairperson, said in a statement accompanying the results. " There remains work to do."
This year's results show a marked improvement on 2014's tests, which had a CET1 ratio pass mark of 5.5. percent.
Unlike previous tests there are no pass-or-fail rankings this year. Instead the results will be passed on by the EBA to individual country regulators. The results were put out late Friday night in Europe to allow the European Central Bank, authorities and investors to plot their next move.
The level of non-performing loans across Europe has become a major concern for investors, and global regulators including the International Monetary Fund.
"We have 1 trillion (euro) of NPLs - it's a big figure," Andrea Enria, chairman of the European Banking Authority (EBA), told CNBC ahead of the tests' publication.
"The level has started decreasing in all countries. The point is the pace of adjustment. Are we adjusting the levels fast enough? You don't want to be too fast, because then you have a massive capital impasse and fire sale of assets, but you don't want to be too slow, because then the banks would be unable to lend and remain unprofitable for long periods of time."
Concerns have been raised over Germany's Deutsche Bank, whose shares have been falling sharply, down 46 percent since the start of the year, since the U.K. voted to leave the EU last month. Adding to the worries, the second-quarter earnings showed profits fell sharply to 987 million euros ($1095 million) from 2.7 billion euros in the first half of the year.
However, the bank fared better than expected in the EBA results, with a transitional CET1 ratio of 7.69 percent. In after-hours trading, the bank's shares were up 1.5 percent.
Catherine Boyle and Spriha Srivastava contributed to this report.