Nisa boss Nick Read has quit the convenience chain and wholesaler after almost three years at the helm.
The former Tesco executive, who returned the member-owned business to profit after taking the reins in December 2014, stepped down just days before the Co-op was expected to make a formal offer for the company.
Nisa has kicked off a search for Read’s replacement and said it would unveil his successor “in due course”.
The business had attracted takeover interest from Sainsbury’s but is now in exclusive talks with the Co-op about a potential £140m deal.
Sources close to the situation said Read’s exit would not have an impact on the proposed acquisition.
Read joined at Nisa what the company called “a very challenging time”, as it posted an unexpected full-year loss.
He drafted in Robin Brown as finance boss in May 2015 and transformed its strategy.
In July last year, Nisa reported an EBITDA of £7.3m – marking the largest annual swing in its 40-year history as it returned to profitability.
EBITDA increased to £8.6m this year, as pre-tax profit reached £2.8m.
In the wake of Tesco’s £3.7bn swoop for wholesale giant Booker, those financial figures have made Nisa a viable takeover target for other grocers seeking to further consolidate the food market.
Tesco’s big four rival Morrisons has penned a supply deal with McColl’s, while Costcutter’s parent company Bibby Line Group said in August that it was “exploring all options available” for the c-store chain.
Any acquisition of Scunthorpe-based Nisa must be approved by the majority of its 1,400 members.
Read said: “My time at Nisa has been both challenging and eventful, and I am proud of our collective success in turning the business round.
“The return to profitable growth was key to creating the confidence that enabled a sustainable business model for the benefit of all Nisa members.
“I am grateful for all the support I have received from colleagues and members.”
Nisa chairman Peter Hartley added: “We are grateful to Nick for his leadership during a challenging period for Nisa and the wider convenience sector.
“Nick and his team have brought much needed stability to Nisa, and he will leave the business in a significantly improved financial position.”