Huge numbers can be scary, especially when it comes to derivatives. So investors should take a seat before reading third-quarter securities filings from some of the biggest US banks.

During the period, gross derivatives assets jumped 52% at Bank of America from the previous quarter, to $2.17trillion. At JP Morgan Chase, they rose 47%, to $2.04 trillion. And at Citigroup, they increased 31%, to about $1.1trillion.