Mostly True
The Korean stock market experienced a sharp single-day decline, with the KOSPI index falling 7 percent in what has been widely described as a "Black Thursday" market rout, according to a fact-check review of five primary sources.
The claim centers on a steep one-day plunge of the KOSPI benchmark index, in which the market lost 7 percent of its value in a single trading session. The scale of the fall was severe enough that the session has come to be referred to in Korean market commentary as "Black Thursday."
A fact-check report on the claim, stored under the file name reports/2026-10-15_코스피7퍼센트_검은목요일_팩트체크.md, reviewed five primary sources before reaching its final judgment. The review concluded that the core assertion — that the KOSPI fell 7 percent on the day dubbed Black Thursday — is substantially accurate, though the "Black Thursday" label itself reflects popular characterization rather than a formal market designation.
The final assessment of the claim is Mostly True.