In contrast to the early days of the 2008 financial crisis, when tech was culled to cut costs, digital upgrades are now seen as both an operational necessity and a strategic differentiator. Tech spending in global-markets divisions of investment banks has risen to $16.5 billion at the 12 institutions Coalition canvassed, from $13.8 billion in 2013. A chunk of that is maintenance of bulky legacy systems, but Amrit Shahani, a London-based research director at Coalition, says large Wall Street and European banks are each spending around 10 per cent, or a giddy $1 billion of their annual revenue, to stay relevant.