Cash earnings from Westpac's institutional bank tanked for a second year in a row over the full year to September 2016, leaving a division that was once a powerhouse of the group to produce earnings little better than one quarter of those of its retail franchises.Earnings fell to A$1.1 billion at WIB, down from $1.3 billion in 2015 and $1.5 billion in 2014.The return on equity over 2016 at WIB was 11.0 per cent, down from 13.8 per cent in 2015. This return is 300 basis points below the group return and the lowest for any division of the bank.On the other hand, WIB's cash earnings lifted over the second half of 2016 as impairment charges fell. The second half WIB profit was $581 million compared with $517 million in the first half, Westpac said.The asset quality story may not hold, with stressed assets as a percentage of gross loans in WIB jumping to 88 bps at September 2016, up 11 bps over six months.Amid management talk of the priority on returns and high margin advisory and transactional work, the loan run off at WIB was slight, down $1 billion to $74 million.