The trading accounts of US banks topped $1tn in the third quarter — their highest level in more than 16 years and close to an all-time high — as the nation’s largest financial firms seek to profit from rebuilding their market-making businesses.

That growth has at the same time left the banks, particularly the largest ones, more exposed to market moves than at any time since the financial crisis as they hold ever-greater inventories of price-sensitive securities.

Their trading accounts last peaked at just over $1tn, slightly higher than today, in the first quarter of 2008, according to industry tracker BankRegData. That was just a few months before the bursting of the housing bubble that led to a credit crunch, cratered markets and sent the US into a significant recession.