Complex sentence: The most significant parent company defendant is Anglo American South Africa Limited, which has now divested itself of all its gold mining assets but, for several decades, owned and controlled gold mine owning subsidiaries responsible for about 40% of South Africa's gold production.
Split into simpler sentences: The most significant parent company defendant is Anglo American South Africa Limited. AASA has now divested itself of all its gold mining assets, but for several decades owned and controlled gold mine owning subsidiaries responsible for about 40% of South Africa's gold production.