Castlefield AIM Stock Story: Impax Asset Management

By David Gorman

In this featured stock story, Castlefield's David Gorman introduces the specialist asset manager AIM-listed holding Impax Asset Management.


Impax Asset Management is a specialist asset manager investing predominantly in companies which support the transition to a more sustainable economy. Founded in 1998 and listed on AIM in 2001, the company offers a range of investment strategies and products and, as of February 2024, has assets under management of over £39 billion.

Impax has offices in the UK, Ireland, the US and in Asia which all serve global clients. The firm’s wide range of funds includes Impax Environmental Markets PLC as well as many other strategies such as Listed Infrastructure, Global Social Leader and Global Women’s Leadership. The driving force behind the company is the founder and current Chief Executive Ian Simm. Ian is a respected industry figure and his firm is very much a thought leader in the sustainable investment industry.

We share the company’s view that investment markets are shaped by global sustainability challenges, especially climate change, pollution, pressure on natural resources as well as human issues such as demographics and gender equality.

Ian’s philosophy is that, on a finite planet with an expanding population seeking ever higher standards of living, the transition to a more sustainable economy is practically inevitable. Furthermore, “this transition will continue to provide excellent investment opportunities for red-blooded capitalists and ethically motivated investors alike.”

Impax Environmental Markets, itself listed on the London Stock Exchange, invests in companies that are developing new solutions to resource challenges. One of its larger holdings is in Stericycle, a global leader in the management of clinical waste in hospitals and clinics, protecting the well-being of patients and staff. Impax is always innovating and its new Global Social Leaders Strategy will seek out companies with a strong corporate culture, exemplified by factors such as low employee turnover and a higher-than-average percentage of women in leadership roles.

this transition will continue to provide excellent investment opportunities for red-blooded capitalists and ethically motivated investors alike.

The latest annual results published by Impax showed pleasing progress in the growth of assets under management, especially after what was a challenging 2023 financial year. However, along with that of many other smaller companies, the Impax share price has endured a difficult couple of years as a headline rally in global equity markets masked weaker sentiment in many areas of the global economy and a “risk-off” attitude among investors. Nevertheless, we believe Impax’s focus on the industries of the future should see the shares make progress over time.