4  The mergers and acquisitions example suggests a somewhat different source of competitive advantage for certain firms, arising from the fact that a firm may, over time, acquire sufficient experience that it can provide,  2  BIS central bankers’ speeches  The paucity of empirical work means we can only hypothesize these scale and scope economies, though intuition and observation may make some hypotheses stronger than others.
Even assuming, as I think reasonable, that most or all the economies I have identified would hold up to empirical assessment, the crucial questions would remain as to how big or how integrated financial firms need to be in order to attain these economies. The relative dearth of work that would help answer these questions can be attributed to a number of factors.