The KOSPI index is displayed at a dealing room of Hana Bank in Seoul, Friday. Newsis

Seoul shares traded nearly 4 percent lower as investors locked in profits from a recent tech-led rally while monitoring uncertainty over U.S.-Iran peace negotiations.

After opening 3.44 percent lower, the Korea Composite Stock Price Index (KOSPI) lost 334.97 points, or 3.88 percent, to 8,304.44 as of 11:20 a.m., recovering some of its earlier losses after plunging as much as 6.88 percent.

The Korea Exchange suspended program trading for the KOSPI for five minutes at around 9:08 a.m., a measure issued when the KOSPI 200 Futures index decreases 5 percent or more for at least one minute.

Overnight, major U.S. stocks closed mixed.