Officials at Anglo American Platinum (Amplats), hit hard after South Africa’s longest mining strike that concluded last week, have announced plans to sell their mines to divest $4 billion in assets, The Sunday Times reported. In all, Amplats lost $1.1 billion over the five-month walkout.

The unit has hired a U.K. bank to auction its mines in the prolific Rustenburg region operating since the 1950s, according to the Johannesburg paper. Together with Impala Platinum and Lonmin plc, Amplats’ area projects represent 40% of global platinum output.

“We have been clear that a number of assets in the portfolio are unlikely to satisfy our stated return criteria and will be divested at the right time,” Anglo American spokesman James Wyatt-Tilby said in an email message to Bloomberg, declining to comment further.