Waste management speciaist Augean dropped on the news its Chief Executive was stepping down after five years in charge.
It also reported that it did not expect significant growth in its core markets for the remainder of the year, but it would meet expectations.
The firm said that CEO Paul Blackler intended to leave the group to "explore a new, unrelated opportunity in the energy and renewables sector".
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The company is set to engage a headhunter to find a replacement, but added that a combination of Blackler's "appropriate notice period" and current management capacity within the business, would ensure a smooth transition to the successor.
Chairman Jim Meredith said: "Paul has made a significant contribution to the Augean business over the past five years and whilst I am disappointed to see him leave I would like to thank him for that contribution and wish him well for the next stage of his career".
The announcement came as the company reported its first half results.
Net revenue increased to £17.5m, up from £16.0m the year before, while adjusted profit before tax increased to £0.9m from a loss of £0.1m in 2011.
The firm said it did not expect significant growth in its core markets over the remainder of the year.
However, it said the board remained confident the company was on track to meet expectations for the full year.
Shares were down almost 6% by 1400 on Tuesday.
