South Korea's experiment with leveraged single-stock ETFs has shown how quickly passive investing, concentrated markets and retail speculation can feed on one another

South Korea's experiment with leveraged single-stock ETFs has shown how quickly passive investing, concentrated markets and retail speculation can feed on one another

South Korea's leveraged chip ETFs grew from $3B to $9.1B in weeks before a regulator's public regret triggered a KOSPI circuit breaker and global sell-off.