Adcock is the subject of a 1.2 billion dollar takeover battle between Chilean company CFR Pharmaceuticals, which is looking to extend its reach into fast-growing Africa, and local conglomerate Bidvest.
Santiago-based CFR Pharmaceuticals' cash and shares offer for Adcock was worth around 12.9 billion rand (1.24 billion dollars), or 73.51 rand per share, on Friday, while Bidvest has countered by offering 70 rand a share in cash for around a third of Adcock, which would give it a big enough stake to block the CFR deal.
Shares in Adcock were trading up 0.4 per cent at 71.01 rand by 1228 GMT on Friday.
CFR, needs backing from shareholders holding 75 per cent of the company at a meeting on Dec. 18.
“In terms of the CFR offer, we believed the CFR shares were expensive and carried a higher risk," Oasis spokesman Hassan Motala said.
Bidvest's chief executive Brian Joffe said earlier this week his company held about 4.5 per cent of Adcock.
Meanwhile state pension fund the Public Investment Corporation has also rejected the CFR offer. PIC, which manages the pension funds of government employees, is the top shareholder in both Adcock, with 18.9 per cent, and Bidvest, with 15 per cent.
With PIC's backing for its opposition to the CFR offer Bidvest would only need a further 6.2 per cent of Adcock to stop the deal.
Hassan declined to comment on who bought Oasis's stake.
JSE data showed that 3.86 million shares, or about 2.2 per cent of Adcock had been traded off the exchange's central order book.