Over the past couple of months, the ECB has collected vast streams of data from the 128 banks that are taking part in the exercise, and a deadline for some lenders to deliver extensive detail on their trading books and risk models is approaching.
National supervisors have also identified particularly risky portfolios they would like included in the in-depth review, which the ECB now needs to review and approve.
In Germany, for example, shipping is likely to be looked at closely. The country was a global leader in ship lending before the financial crisis struck and the global economic downturn crimped trade flows, wiping out the profits that shippers need to pay off their loans.
Over the next couple of months, ECB inspectors will make sure the lenders have set aside sufficient capital for possible loan losses, check for data accuracy and run on-site reviews - the most complex part of the assessment.
(Read more: Euro zone money supply dries up, pressuring Draghi)
Banks and investors are keen to find out how the ECB will go about this stage, which portfolios and assets will be looked at, and how the ECB defines certain key criteria, such as when a loan has gone bad.
Morgan Stanley sees Italy, the Netherlands and Austria in focus when it comes to non-performing loans, arguing that in Italy these continue to grow with no slowdown seen.
Italian lenders have been hard hitby write downs on soured loans as the country's deepest recession in 60 years takes its toll on households and businesses.
Federico Ghizzoni, head of Italy's top lender UniCredit told Reuters TV last month the AQR would reveal that some smaller Italian lenders need additional capital, and that it could also trigger a new consolidation wave among them.
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