SK Telecom, South Korea's top mobile firm, after being unsuccessful in a market it had once had high hopes from, has sold back its stake in China Unicom for $1.3 billion.

This recent step by SK Telecom comes after a move by China's second-largest mobile operator and Spain's Telefonica to deepen ties.

Daniel Jin, an analyst at Shinhan Investment Corp said: "Telefonica and SK Telecom unexpectedly emerged as bedfellows in China's No. 2 mobile carrier after an overhaul of China's telecom industry this year, which saw the country's four main carriers reduced to three."

Jin added, "Although SK still has some investments in China, they are on a relatively small scale. They are essentially collecting their investment back (with this deal)."

The SK group's present priorities include the release of a credit card joint venture with the country's No. 4 lender Hana Financial Group; and Jin specified that the move was in line with these priorities. SK tried for years to establish itself in the Chinese mobile market.

On Monday, a statement passed by SK Telecom, said that the sale followed a "change of strategy," and the proceeds would be used to strengthen its financial base and tap new business opportunities.

SK intends creating a practical business model in China by cooperating with various operators, including China Unicom.

A 3.8 percent stake from SK Telecom would be bought back by China Unicom at HK$11.105 per share, for a total of about HK$10 billion ($1.29 billion).

SK Telecom's shares closed 2.9 percent higher, compared to a 0.9 percent fall in the wider market.

Unicom sold its CDMA network to China Telecom, under China's telecom reform. It should be noted that the tie-up made less sense than an alliance with Telefonica, which uses GSM and WCDMA standards, as SK Telecom specializes in CDMA (code division multiple access) technology.