The euro area's biggest banks will show a €6 billion capital gap in the European Central Bank's tests of the quality of their assets and ability to withstand economic shocks, said Citigroup.

The shortfall would be €15 billion when excluding capital banks raised this year, London-based Citigroup analysts led by Ronit Ghose wrote in an e-mailed report. They said their stress tests of 37 lenders used more conservative definitions of non-performing loans than the ECB, which is examining 130 firms.

Failures will be concentrated in Greece, Italy, Spain and Ireland, according to Citigroup. While at least three Greek banks will fail, their actual deficit will be “small” following measures taken in 2014, the analysts wrote. Two Spanish lenders will probably show “material” adjustments after the asset quality review as the ECB disputes the status of their restructured loans and provisioning, they said.

Any discrepancies the ECB identifies in the books of German banks will probably center on “risky” areas like shipping loans, while the focus for their French competitors lies in credit in central and eastern Europe, Citigroup said. Banks from both countries will see their level three assets, loans and securities so complex that they can only be valued with internal models, under scrutiny, the analysts said.