Patrick Soon-Shiong, the billionaire doctor-turned-investor, has upped his stake in graphene-based products maker Directa Plus PLC (LON:DCTA) to 28.89%.
Soon-Shiong first went bargain-hunting on London’s alternative investment market in February, when he purchased 18.85% of Directa’s shares.
Subsequently, his interest rose to 22.15% before he went shopping again on Friday to take his stake in the materials company to just below the level where he will have to make a mandatory offer.
Graphene is a stronger-than-diamonds material that Directa is using to enhance a range of products from clothes to tyres.
Soon-Shiong is the owner of the LA Times as well as a handful of other regional newspapers.
The entrepreneur also owns firms NantEnergy, which has developed a zinc-air rechargeable battery to replace the standard lithium ion type, and NantWorks, which develops immuno-therapies and cancer tests.
The South African-born investor started as a surgeon in Los Angeles in 1980s and made his money by developing cancer drug Abraxane, which he then folded into his own company American Pharmaceutical Partners (APP).
Abraxane got its FDA approval in 2005 and over the next five years APP was split in two, with Soon-Shiong owning around 80% of each, with each half subsequently sold off to Fresenius and Celgene respectively for £6.9bn in total.
A week ago, Directa Plus completed a placing and open offer that raised £7.6mln at 75p per share.
Shares in the graphene group were trading at 72.5p today.