It started with a $105 billion ($132 billion) blunder, and then it got worse.

Someone at Samsung Securities, one of South Korea's largest brokerages, was trying to pay employees 1,000 won ($1.10) per share in dividends under a company compensation plan. Somehow, they gave them 1,000 Samsung Securities shares instead.

Share sell-off: A trader in Seoul, South Korea. Credit:AP

In total, the company distributed 2.83 billion shares, worth -- on paper -- about 112.6 trillion won. That was more than 30 times the company's market value.

The fact that the shares didn't exist didn't stop 16 employees from selling them. And that spurred a rout in Samsung Securities' stock. It plunged as much as 12 per cent in the space of minutes on April 6, the biggest decline since the global financial crisis. Many retail investors got burned.