SEOUL (Reuters) - Samsung Securities Co 016360.KS Chief Executive Officer Koo Sung-hoon resigned after the company was punished by South Korea's financial regulator because an employee's error sparked a $105 billion "ghost stock" blunder, the company said in a regulatory filing on Friday.

Koo’s departure came a day after South Korea’s financial watchdog handed down a six month partial suspension of the brokerage’s operations and suspended its chief from his duties for three months over the fat finger error.

The regulatory filing did not provide further details.

Samsung Securities in April accidentally issued 2.8 billion shares to employees - more than 30 times the number of its outstanding shares and theoretically worth some $100 billion - some of which were quickly sold off by workers.

The company was not immediately reachable for comment.