Shares of SA investment holding company HCI gained the most in four weeks on Tuesday on a Norwegian news report that a Namibian offshore field it holds a 10% stake in could be the world’s largest ever deep-sea oilfield.  

The field called Venus-1X off the Namibian coastline may have as many as 13-billion barrels of oil and more than 10-trillion cubic feet of natural gas, authoritative Norwegian specialist energy and oil publication Upstream reported...