Naspers was tracking a surge in its Chinese money spinner Tencent Holdings.
Naspers, which owns about a third of China's biggest internet firm, climbed 4.42 percent to 1,085.95. Tencent jumped more than 5 percent overnight ahead of its quarterly results on Wednesday.
But African Bank plunged 8.53 percent to 8.69 – its weakest level in 10 years - extending the sharp decline since last week when it flagged a 3.3 billion rand ($317.70 million)first-half loss to more than 30 percent.
"Management of African Bank is struggling to lay down investors' fears and I am of the opinion that there's another rights issue coming. It's not going be at 10 rand or 9 rand, it would be closer to 6 rand," said Evan Giannakis, trader at Imara SP Reid.
Overall, investors took their cue from an upbeat tone in major overseas markets and higher metal prices such as copper and gold.
The JSE Top-40 index was up 0.9 percent at 44,135.65 after setting a record 44,223.99. The broader
All-share index gained 0.79 percent to 49,239.29, pulling back from a record 49,327.96 set during the session.
Trading volumes were average with 186 million shares changing hands. Advancers outnumbered decliners 189 to 114 and 66 shares were unchanged.