In early November 2011, Anglo American entered into talks with the Oppenheimer family to divest the latter's remaining shares of De Beers, whereby Anglo American acquired an additional 40% stake for $5.1 billion, increasing their overall stake to 85%. This came at a time of increased labour strikes and international attention to Oppenheimer's involvement in conflict diamonds. Anglo American then sold a 24.5% share in its Chilean copper unit, Anglo American Sur, to Japan's Mitsubishi Corporation for $5.39 billion, paid with a promissory note due on 10 November 2011. With this deal, the Anglo American Sur complex was valued at $22 billion.