Why everybody is talking about stocks in Korea, and why it's worrisome

At lunch tables, office coffee breaks and weekend family gatherings, conversations increasingly revolve around which shares surged overnight, which semiconductor stock might be the next to double and who made how much money in a single day.

Social media feeds are flooded with screenshots of investors’ portfolios showing eye-popping gains.

Bookstores have turned bestseller sections over to investing guides and stock market strategy books.

Even teenagers are joining the frenzy.

The fever comes as