Berenberg said that there were at least 15 major issues still to be resolved that could lead to separate bank fines of more than €100m ($129m, £79m), in the report published yesterday.
The biggest of these issues were cited as manipulation of currency markets and benchmark interest rates, and US mortgage market claims.
"This year has seen an escalation in the level of fines imposed on banks and it is clear that a significant number of issues remain outstanding. For those lacking suitable buffers, these potential fines will hamper capital return, in our view, and in some situations could trigger capital raising,” it said.
Barclays and Credit Suisse were two of the banks with the smallest buffers against any potential fines, meaning they may have to raise capital by selling shares instead.
The note also said that UBS and HSBC appeared to have the biggest buffers.
In June, BNP Paribas was hit with a record $8.97bn (£5.2bn, €6.5bn) fine for violating US sanctions between 2004 and 2012.
