A ban on short selling shares on Korean bourses for most investors curtailed the practice by nearly 97 percent, data showed Monday.

Institutional investors in South Korean stock market short sold 20.4 billion won ($17.4 million) worth of stocks a day on average from March 16 to end-August, according to data obtained by Democratic Party Rep. Park Kwang-on from the watchdog Financial Supervisory Service.

That was down from 654.2 billion won a day from January to March 13.

Certain authorized institutional investors were exempt from the temporary ban, as their short selling helps provide liquidity to stabilize securities prices.

From March 16 to Aug. 31, Samsung Electronics stocks were short sold the most -- 2.7 billion won on average daily -- followed by virus testing kit maker Seegene, internet giant Kakao and biosimilar firm Celltrion.

Short sellers in the stock market borrow shares and then sell them, hoping to profit by buying them back at a lower price before returning them to their original owner.

An initial six-month short selling ban that lasted until September was extended by another six months, until March 2020. Before the ban was put in place, overseas investors accounted for over 55 percent of short selling this year.

By Son Ji-hyoung (consnow@heraldcorp.com)