. net interest income was relatively flat compared with the prior year , as lower loan yields , lower investment securities net interest income , and lower trading asset balance and yields were offset by higher average loan balances and lower interest expense on deposits . the firm 2019s average interest-earning assets were $ 2.1 trillion in 2015 , and the net interest yield on these assets , on a fully taxable- equivalent ( 201cfte 201d ) basis , was 2.14% ( 2