LONDON--GlaxoSmithKline PLC (GSK.LN) said Friday it has sold 28.2 million shares in South Africa's Aspen Pharmacare Holdings Ltd. (APN.JO) for 372 South African rand a share, raising ZAR10.5 billion ($854 million).

Following the sale, Glaxo will hold 28.2 million ordinary shares in Aspen, about 6.2% of the issued share capital, and has undertaken not to sell any more shares in Aspen for 180 days.

Glaxo plans to use the money raised for general corporate purposes. The net profit on the sale won't be included in core operating profit and earnings per share in 2015, it added.

The pharmaceutical giant said Thursday it would sell about half of its 12.4% stake in Aspen Pharmacare through a placement to investors.

Glaxo Chief Executive Simon Dingemans said Thursday selling the shares in Aspen would give it more financial flexibility following a recent deal with Switzerland's Novartis AG (NVS) that involved selling businesses to each other and setting up a joint venture.

Glaxo took a stake of about 19% in Aspen in 2009 as part of a strategic relationship that included the two companies combining some commercial activities in Sub-Saharan Africa.

In November 2013 Glaxo sold 6.2% of Aspen to investors for ZAR7.1 billion, cutting its stake to the current 12.4%.

"We continue to believe in the strategy of Aspen and we remain committed to working together in the future," he added Thursday.

Write to Rory Gallivan at rory.gallivan@wsj.com; Twitter: @RoryGallivan

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