Two years after spending $12 billion buying St George Bank, the chief executive of Westpac Banking Corp , Gail Kelly , is finally moving to maximise the financial benefits of the merger by attacking the subsidiary’s $1 billion a year in expenses.

The move to crank up the returns from St George by achieving greater efficiencies could not have come at a better time. Westpac’s shares have been belted ever since it revealed a decline in its net interest margin from 2.39 per cent in September 2009 to 2.28 per cent in March 2010.