Shares of Renergen rose the most in almost four months on Monday, after the helium and natural gas group said the Central Energy Fund (CEF) is looking to pick up a R1bn stake, making it the second high-profile investor to express interest in about two weeks.

The state-owned CEF, whose mandate includes securing SA energy security, aims to pick up a 10% stake in Renergen’s subsidiary Tetra4, which wholly owns the Virginia Gas Project in the Free State...