The US Federal Reserve is carrying out its first ever system-wide stress test of bank liquidity in a move that could force banks to change their funding sources.

Known internally as “C-Lar” – the liquidity version of the Fed’s annual “comprehensive capital analysis and review” – the examination only began recently. According to people familiar with the matter, it covers at least the 19 banks subject to the capital tests as well as some of the largest foreign banks with US operations.

The new exercise is a sign that the Fed is stepping up its scrutiny of liquidity – one of the biggest issues revealed by the 2008 financial crisis – and testing not just access to cash at individual banks but how they would fare under system-wide financial stress.