Jane Fraser, chief executive of Citi since March 2021, has a mighty task on her hands. Like so many of her predecessors, she faces the puzzle of how to articulate an identity for a bank that always seems to be trying to do too much at once. So far, she has focused on redefining the scope of the firm and most recently on adapting its structure to fit that. The hardest part – fixing the bank’s woeful returns – is still to come.