Samsung's Korean stock trading arm is in turmoil after a A$140 billion ($147b) "fat finger" mistake.

Last Friday, a Samsung Securities employee accidentally caused the company to pay out the massive dividend in the form of its own shares to more than 2000 employees who were members of the company stock-ownership scheme, The Wall Street Journal reported.

According to the paper, the dividend was supposed to be 1000 won ($1.27) per share, but the employee mistook the form of measurement, confusing won for shares, leading the company to issue a dividend that was 1000 times the value of each share held by the employees.

The mistake saw the company deposit 2.8 billion shares worth 111.8 trillion won — more than 30 times the company's existing issued shares — into employee accounts.

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Shortly after receiving them, 16 staff members sold five million shares worth about A$241 million. It took Samsung Securities 37 minutes to completely block employees from selling the accidental shares.

"We will actively compensate investors who suffered as a result of the temporary sale," a Samsung Securities spokeswoman said on Tuesday.

South Korea's Financial Supervisory Services watchdog called the incident "a major financial accident that has severely undermined the safety and trust of the capital market" and said it would launch an investigation.

The country's National Pension Service, the world's fourth-largest pension fund, said it would cut ties with Samsung Securities due to "concerns of poor safety measures following the financial accident".