For several years, it's been received wisdom that post-crisis regulation would constrain market-makers and their profits - it was a question of when, rather than if. For many, proof came in late-May and June this year after US Federal Reserve chairman, Ben Bernanke, warned the US may start to rein in its bond-buying programme. The resulting volatility was due in part to a lack of market-making liquidity, the argument goes.
But banks are divided on the issue. "Questions about dealer appetite are