Foreigners' stock holdings in South Korea's tech-heavy KOSDAQ bourse surged 52.5 percent last month from 14 months earlier to buttress its recent rally, the financial watchdog said Thursday.

Their stock ownership came to 18 trillion won ($16.4 billion) as of end-February, compared with 11.8 trillion won tallied at the end of 2013, according to the Financial Supervisory Service.

Their holdings accounted for 10.8 percent of the total market capitalization of 166.7 trillion won.

During the 14-month period, the KOSDAQ jumped 24.9 percent to 624.56 points from 499.99. It closed at a nearly seven-year high of 630.35 on Wednesday,

The benchmark KOSPI had 417.8 trillion won worth of foreign investment as of end-February, taking up 33.8 percent of the total cap of 1,235.2 trillion won.

Foreigners had bought a net 1 trillion won worth of KOSDAQ-listed shares throughout 2014 but turned net sellers in the first two months of 2015.

U.S. investors were the biggest buyers on the secondary bourse, scooping up a net 800 billion won over the 14-month period, while Europeans offloaded a net 10 billion won.

On the top bourse, Europeans dumped a net 8.7 trillion won worth of shares, offsetting Asian and U.S. investors' net buying of 7.4 trillion won and 3.3 trillion won, respectively. (Yonhap)