South Korea's key stock index has posted the second-highest profit rate among its Group of 20 peers since this year's bottom, helped by robust buying by individuals, the bourse operator said Sunday.

The benchmark Korea Composite Stock Price Index (KOSPI) closed at 2,396.69 points Friday, soaring 64.42 percent from 1,439.43 on March 19.

All G-20 countries saw their main stock indices plunge to the year's lowest in mid-March, when investors' fear peaked over the new coronavirus pandemic.

The gain marks the second-highest rate only after Argentina's 107.54 percent, the Korea Exchange (KRX) said.

Among advanced economies, Germany gained 56.4 percent, with Japan advancing 41.4 percent and France adding 34.07 percent. Among emerging economies, Brazil added 54.73 percent, with India and Russia up 49.55 percent and 46.96 percent, respectively.

Of the Wall Street peers, the Nasdaq rose 58.2 percent. The S&P 500 rose 49.32 percent, with the Dow Jones Industrial Average up 48.8 percent.

Global financial markets are still struggling to recover from the economic fallout of COVID-19, data showed. Only four G-20 members -- South Korea, Argentina, the United States and China -- saw their key stock gauges go up from a year ago.

Local experts attributed the KOSPI's surge to the brisk investment by retail investors.

Since March 19 to Sept. 11, individuals bought a net 25.8 trillion won ($21.7 billion) worth of local stocks, while foreigners sold a net 14.9 trillion won. Institutions offloaded a net 11.9 trillion won.

"The biggest push came from huge direct investment by individuals," said Kyobo Securities senior researcher Kim Hyung-ryeol.

"The current low-interest environment caused a massive inflow of cash into the local stock markets," he added.

Investors' desposits at brokerages stood at 57.4 trillion won as of Friday, according to the data from the Korea Financial Investment Association (KOFIA). (Yonhap)