Investment management firm Tyndall is looking for a new chief executive only seven months after appointing Barry Sheehan.

Sheehan, who joined the group from HSBC Asset Management in March, last week announced he was stepping down following a serious gym injury. He will move into an executive director position and will continue to implement the group's new business strategy.

"We are around two-thirds of the way through the process, with further strategies and changes to be rolled out in the next few months," he said. "I remain intimately involved in this, as well as in the recruitment and selection of a replacement managing director.

"I will reassess my position with Promina chief executive Dennis Fox and the new chief executive once the process of strategy implementation is complete and decide what duties, if any, I will have going forward from there.

"It was a tough call but it was the best decision for both me and the business."

While expressing his disappointment, Fox agreed it was the best outcome for Tyndall given the circumstances.

"I'm pleased we have found a means to maintain Barry's involvement and continue to access his experience and extensive knowledge while we refine and finalise Tyndall's business plan," he said. Tyndall will start looking for a replacement immediately.

"We are not in any hurry as I'm not going anywhere for now," Sheehan said. "It's more about getting the right candidate."

His mobility has been restricted following the injury and two subsequent surgeries and he is undergoing extensive rehabilitation.