SK Telecom, South Korea's top mobile carrier, posted a worse-than-expected 26% drop in quarterly profit, hit by higher marketing costs and stalling growth in data revenue.

SK Telecom, South Korea's top mobile carrier, said on Thursday it was not planning to buy a controlling stake in any major U.S. mobile operator, brushing off earlier reports that it was seeking a stake in Sprint Nextel.

SK Telecom, the largest provider of wireless phone service in South Korea, is in talks to acquire Sprint Nextel, the troubled U.S. wireless carrier, according to people familiar with the talks.

Virgin Mobile USA is set to acquire a U.S. mobile arm of South Korea's SK Telecom as both sides agreed to combine their struggling businesses, the Financial Times reported on Wednesday.