Johannesburg - Naspers [JSE:NPN] has extended losses on Friday, as the market continues to be worried about the growth plan of Chinese firm Tencent in which it has a 30% stake. Naspers shares traded 3.12% lower at R354.60, becoming the biggest percentage loser among Johannesburg's Top 40 index of blue chips. On Thursday, Naspers fell 4.4% to R366.01 after Tencent posted slower profit growth. "I think this is what is still driving the share price," said a trader. Tencent's blockbuster growth has been a big contributor to the performance of the media firm, which is heavily invested in emerging markets and e-commerce internet companies.The Top 40 blue chip index has gained more than 1%, tracking global equity markets, with miners adding the most points to the index as commodity prices cruise higher. The benchmark index is up 1.02% at 27 947.92 points and the broader All-share index is 0.88% better at 30 988.39 points.