THE Hong Kong branch of Swiss Bank Corp (SBC) yesterday launched a $259 million covered warrant issue on Hongkong Land. The issue, which came after the close of trading on the stock exchange, is for 350 million warrants priced at 74 cents each. The warrants have a gearing of 3.49 and a conversion premium of 18.22 per cent. They mature on January 2, 1996. SBC last night reported strong demand for the issue in the derivatives market. ''The strong domestic demand for the issue illustrates the increasingly sophisticated and international nature of the Hong Kong stock market,'' said SBCI Finance Asia director Daniel Poon. An application will be made to list the warrants in Hong Kong. The issue follows successful SBC issues in recent months on Hongkong Telecom, Henderson Land Development and HSBC Holdings. SBC said it was responding to strong market demand for covered warrants on strong blue-chip counters.