Warner is leaving to "concentrate on his other business interests" and a search for his replacement is already underway. "A further announcement will be made in due course," the company said.
"Ed has chaired the company with professionalism and dedication and we are grateful for his contribution over the past six years and wish him well with his many other roles in the future," Phillip Wale, Panmure's chief executive, said.
Panmure's share price has dropped by nearly 65 per cent in the last six months, as the stoke broker and investment bank has battled against stock market volatility.
Back in December Panmure's share price plummeted nearly 40 per cent in one day as the company announced it would make a loss.
Wale said at the time: "Deferment of deal-flow has led to a disappointing end to the year, However we look forward to an encouraging start to the first half of 2016."
Better times may be on the horizon as in January the small cap specialist broker broke into the top five City advisers chart as financial data publisher Adviser Rankings unveiled its tenth annual corporate advisers rankings for 2015.