Wells Fargo has some explaining to do

Wells Fargo has a lot of explaining to do.

The bank, once the largest bank in the US by market cap, and its CEO John Stumpf have been raked over the coals following the revelation that 2 million accounts were opened without customers' knowledge between 2011 and 2015.

According to Mike Mayo, a banking analyst at CLSA, even after Stumpf's testimony on Capitol Hill, there are still some important questions the bank has to answer.

"Shareholders have a right to know what will be done to the pay of top executives, to the composition of the board, and for impacted customers," said Mayo in a note to clients. "We believe Wells Fargo is bigger than the CEO, notwithstanding a good financial track record during his tenure, and there should be no more excuses for the lack of answers to key questions."

Mayo asserted that his support of Stumpf is "wavering" and there are five key questions Stumpf has to answer in order to win back his trust. They are:

1. Clarify why the issues went on for years: "Wells needs to clarify how and why these problems could continue for so long, so that investors are assured these problems are resolved."
2. Give specifics on how it's helping customers: "Wells needs to specify what it is doing to help impacted customers. (Also, what percentage of impacted customers remains at Wells?)"
3. Put measures in place to take back executive stock: "Clawbacks should be put in place or, at a bare minimum, Wells should provide a timeline for these decisions."
4. Stumpf should lower his pay: "The CEO should voluntarily reduce his compensation for the current calendar year."
5. Shake up the Board of Directors: "Wells needs to restructure the board, with changes on the Corporate Responsibility Committee and Human Resources Committee (we think both failed shareholders in terms of oversight and incentives), and possibly splitting the Chair from the CEO."

Additionally, Mayo said that Wells Fargo can move on from Stumpf if need be, citing the strength of the underlying business.

"[Stumpf] may still be the best to provide closure on the regulatory, legal and political issues," said Mayo in the note. "Yet Wells Fargo has been around since 1852 and should show improving financials over the next couple years regardless of who is on top."

With claims from former bank employees about the high-pressure sales culture and the compensation of Carrie Tolstedt, the head of the community banking division where the fraud occurred, still to be resolved it appears the scandal isn't going away anytime soon.