Why two senior executives were departed from the CBA on Monday remains confidential and CEO Ralph Norris is keeping it that way — but he is taking full responsibility for having to unwind a dubious treasury and trading structure that he only signed off on a year ago, raising a question about how much the board and senior management really understand about risk.

Upsetting the basically favourable story being told in the annual results briefing, it was put to Norris that two executives were “terminated with cause” on Monday. What was the cause?

The CEO cautiously replied that two individuals had left the organisation and the reason why was confidential — but it had nothing to do with rumours of trading losses.

Which of course doesn’t answer the question. Monday’s brief statement that executive general manager global markets and treasury, Marten Touw, and general manager products and trading, Vincent Hua, “were leaving” has not be widely examined amidst so much greater turmoil in markets this week.

“Following these departures, the bank has separated responsibility for its Treasury and Global Market functions,” said the bank, but that might be putting the cart before the horse.

The line put out by CBA spinners before today was that the sackings were about a “clash of cultures“, but there seems to have been some unexplained and unsatisfactory business in the CBA over the past two years.

The surprise is not that the inherently unsatisfactory combining of treasury and trading responsibilities is being instantly unwound, but that it was ever combined.

Asked if the change was at APRA’s request, Norris said the regulator had been shown two reviews conducted of the structure and had commented on them, but the CBA had made its own decision.

There have been suggestions Marten Touw was reporting very nice profits out of treasury and that the board and senior management agreed to give him much greater power by combining treasury with the bank’s trading operation. Those who warned against the structure did themselves no career favours.

For some reason, first PWC and then Manhattan Group were called in to review the new structure and obviously found it seriously wanting.

Could there have been an issue of transfer pricing by treasury to obtain such attractive numbers, albeit at the expense of other bank divisions? Norris said transfer pricing by treasury had been reviewed but has not been changed.

So it all remains a bit of a mystery, but a source of concern that the new CEO and board would have gone along with a plan that APRA, PWC and Manhattan found wanting.

Norris said he takes full responsibility for it, which might come as a relief for CBA’s group executive premium business services, Stuart Grimshaw.