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thresholds mapped against number of banks by size, up to £50b ( deposit - takers ) sources : snl capital iq, crr, bcbs, pra rulebook, eba technical standards, supervisory statements, and statements of policy. note : only includes thresholds that are either set using assets / deposits values, or can be translated into assets / deposits values. the y - axis corresponds to the proportion of thresholds / banks below the £ value for assets / deposits on the x - axis. i invite views on this picture, but offer two preliminary observations myself. first, as everyone in banking knows, by number we have a concentration of firms at relatively low asset sizes. whether this is a result of proportionality – our efforts to lower barriers to entry – or barriers to growth is a key question. second, more novel if perhaps less fundamental : there appear to be minor discontinuities around the thresholds of £5b, £10b and £25b, and a more substantial flattening and bump at £50b. these may be worth investigating further. all speeches are available online at www. bankofengland. co. uk / news / speeches complexity another thing we ’ ve been looking at afresh is the complexity of our prudential rules. the scale of the global financial crisis resulted in part from the huge complexity of the financial system, and the many gaps in the rules that sought to regulate it. fixing these gaps required more regulatory constraints and more regulatory discretion – a necessary increase in ‘ essential ’ regulatory complexity. 5 but when should we start worrying about ‘ too much ’ complexity? this is important for at least two reasons : first, excessive complexity may well be counter - productive in terms of our safety and soundness objective6 ; and second, complexity may be anti - competitive if it is harder for small firms to bear the cost of mastering it. designing a framework to trade off costs and benefits of complexity is an emerging research question. but there ’ s a complementary, empirical step : we have wanted to measure the framework ’ s complexity – to say how complex it is. legal and linguistic scholarship suggests the information burden of understanding individual rules, as well as the nature of the interactions between them, both matter here. the measurement debate tends to start with the simple metric of length : how long are our rules? our robot has run the numbers on prudential regulation for banks and tells me that there were about 700, 000 words