Atlas Mara, a sub-Saharan financial services group, announced that Arnold Ekype has stepped down as chairman with co-founder and non-executive director Bob Diamond taking on the role on an interim basis.
Ekpe has decided to resign after his three year-term ends on 1 December 2016, to concentrate on other interests. He is the former boss of the African lender Ecobank and currently serves as a non-executive at the Nigeria Sovereign Investment Authority.
Senior Independent Director Rachel Robbins said: "Having Bob take on the chairmanship on an interim basis will provide a seamless transition of board responsibilities and leadership on all strategic initiatives underway at Atlas Mara."
John Vitalo, who also worked with Diamond at Barclays, continues to run the firm as chief executive.
Diamond set up the company as a joint venture between his Atlas Merchant Capital vehicle and the African conglomerate Mara Group in 2013.
Prior to founding the company, Diamond was the chief executive at Barclays. He was asked to resign after the bank was involved in a Libor fixing scandal during the financial crisis.
Starting a financial-services business in one of the world's poorest regions was "the perfect intersection of doing good and doing well," according to Diamond.
Diamond's venture to build a banking empire in Africa however may be too optimistic, with the share price tumbling 68% since it listed in AIM in 2013.
In order to increase its presence on the continent the company has made four deals, yet its market value has plunged from more than $800m shortly after its initial public offer (IPO) to less than $240m. The group incurred a loss of £6m due to acquisitions costs in 2015.
The commodities boom that had turned Africa into an attractive investment burned out, decreasing the rate of economic growth in the region to a 15-year low.
In an interview with Bloomberg, Diamond said the company is still in its early stages of a "five- to seven-year game" to build its position. "This isn't five-minute rice," he added.
A deal that could salvage the company would be a stake in Barclays African business. According to the same newswire, this deal has however "gone quiet".
"The lower the share moves, the more difficult it becomes for Atlas Mara to do a deal. If they don't get scale, they will fail," says Ayodele Salami, who holds the company's securities.
"You acquire, you protect, and you grow banks during a difficult environment like this-and people are giving a report card now? I think the report card is very strong," Diamond retorted.
Third quarter results for the three months ending 30 September 2-16 will be announced 25 October 2016.
The share price remained stable at $3.40 at 1444 BST on Tuesday.