The trade volume of South Korean shares has markedly dropped on-year in 2016 amid a barrage of setbacks including political turmoil at home and uncertainty over the US interest rate hike, data showed Thursday.

A total of 90.4 billion stocks were traded in the main KOSPI market as of Tuesday, according to the Korea Exchange and the Korea Financial Investment Association.

It marks a 20-percent decline from a year earlier. Trade value also decreased 18 percent to 1,091 trillion won ($912 billion).

The value of stocks traded in the secondary KOSDAQ market fell nearly 7 percent to 813 trillion won.

The trend came despite the extension of stock trade hours by half an hour starting in August.

Market watchers attributed it to weaker investment sentiment, with the market dogged by internal and external woes such as a massive influence-peddling scandal involving President Park Geun-hye, the eurozone trouble and unpredictability about the pace of the US rate hike.

"In recent years, there has been no time like this year that internal and external variations have been palpable," an asset management industry official said. "Stock market participants' sentiment has been frosty."

Stock customers' deposit dipped to around 21.9 trillion won this week after reaching 24 trillion won. (Yonhap)