Seoul Composite Plunges 8.8%, Breaks 5,000 to Trigger Circuit Breaker

The circuit breaker is the detail that matters: Korean authorities halt trading only at extreme thresholds, so this is a mechanical, forced-liquidity event rather than an orderly repricing. The fact that Japan's Nikkei broke a level it had held since May points to a region-wide de-risking rather than a Korea-specific story, which makes the breadth of the move more telling than the size of any single index drop. Whether the selling is concentrated in leveraged or retail-heavy positioning, and whether the circuit breaker's cooling-off period actually restores two-way flow when trading resumes, is the open question.