More than 540-thousand subscribers to SK Telecom(SKT), the country’s largest mobile carrier, were found to have switched to other carriers in the aftermath of a hacking incident that breached their privacy in April.

According to the Korea Telecommunications Operators Association on Friday, 548-thousand-113 subscribers moved to KT and LG Uplus as of Thursday since the massive data breach at SKT on April 22. 

Some 301-thousand had moved to KT and around 246-thousand to LG Uplus. 

The move resulted in SKT’s net loss of 475-thousand-674 subscribers. 

Meanwhile, SKT announced that it had replaced SIM cards for seven-point-49 million subscribers as of 12 a.m. Friday.

Two-point-25 million subscribers have made reservations for SIM card replacement. 

SKT plans to complete the card replacement effort by next Friday.