Shares in CAP-XX (AIM:CPX) rose 7.3% to 0.3p after chairman Dr Graham Cooley purchased 24 million shares at an average price of 0.265p each.
The move lifts his total holding to 603 million shares, representing about 10.41% of the company’s issued share capital.
Cooley, a well-known greentech and technology entrepreneur, joined CAP-XX as non-executive chair earlier this year.
The company is a global leader in supercapacitors and energy storage technology, developing high-performance components for applications including electric vehicles, renewable energy systems and industrial electronics.