What Is Short Selling? Someone Is Borrowing Your Stock to Sell It

On the day SK Hynix crashed through the 2 million won level, analysts were quick to point to heavy short selling as a key culprit. If you're new to investing, you might wonder — is someone actually stealing my shares?

Short selling means selling something you don't own

Short selling is the practice of borrowing shares and selling them, betting the price will fall. Here's how it works step by step: ① Investor A believes SK Hynix will drop, so they borrow 1 share from their broker and sell it for 2,000,000 won. ② The stock falls to 1,600,000 won. A buys it back and returns it to the broker. ③ A pockets a 400,000 won profit. If the stock rises to 2,400,000 won instead, A has to buy it back at a loss — short sellers profit when prices fall, and lose when they rise.

Why does short selling push prices down further?

When short sellers borrow and sell shares, they add supply to the market. More sellers push the price lower. A lower price attracts more shorts, who sell more, pushing the price lower still — a self-reinforcing downward spiral. This is exactly what happened when SK Hynix broke 2 million won. The selloff was amplified further by leveraged ETF liquidations hitting at the same time.

Can regular investors short sell in Korea?

In Korea, short selling has historically been restricted mainly to institutions and foreign investors. Retail participation is limited, complex, and expensive. That's why heavy short interest is often read as a signal that institutional or foreign money has a negative view on the stock.

Is short selling bad?

Not necessarily. Short selling plays a role in deflating price bubbles — it helps bring overpriced stocks back toward fair value when fundamentals don't support the price. That said, the 'uneven playing field' criticism is real. Institutions have broad access to short selling while retail investors face significant barriers, creating an information and access gap that frustrates individual investors. The key takeaway: when short interest rises in a stock you hold, expect short-term selling pressure. Monitoring short data can help you think more clearly about timing and position sizing.