What Is Short Selling?
Short selling is a trading strategy that profits when a security's price falls. The short seller borrows shares from a broker, sells them immediately at the current market price, and later buys the same number of shares back, ideally at a lower price, to return to the lender. The difference between the sale price and the repurchase price is the profit or loss.
It is the mirror image of ordinary investing: instead of buy low, sell high, the short seller sells high first and hopes to buy low afterward.
How It Works
To short a stock, a trader needs a margin account, because the broker requires collateral against the borrowed shares. The short seller pays a borrow fee to the share lender and must also pay over any dividends the stock distributes while the position is open.
The risk profile is asymmetric. The most a short seller can make is 100%, if the stock goes to zero, but losses are unlimited because there is no ceiling on how high a stock can rise. Heavily shorted stocks can also experience a short squeeze, where a rising price forces shorts to buy back shares, pushing the price even higher.
Example
Suppose you short 100 shares of a stock at $50, receiving $5,000 from the sale. If the stock falls to $35, you buy back the 100 shares for $3,500 and pocket $1,500 before borrow fees, a 30% gain on the position.
If instead the stock rallies to $80, buying back costs $8,000 and you lose $3,000, more than half the value of the original sale, and the loss would keep growing if the stock kept climbing.
Why It Matters
Short selling improves market efficiency by letting skeptics express negative views, which helps expose overvalued companies and, at times, outright frauds. Levels of short interest are also a widely watched sentiment indicator.
For finance careers, shorting is central to hedge fund strategies like long/short equity, and understanding borrow costs, squeezes, and margin mechanics is essential for anyone in markets roles.
