A short, in investing, is a trade that profits when a stock’s price goes down. Instead of the familiar “buy low, sell high” approach, short selling flips the order: you sell first at today’s price, then buy later at a lower price, pocketing the difference. It’s one of the few ways to make money in a declining market, but it carries risks that regular stock buying doesn’t.
How Short Selling Works
When you short a stock, you don’t actually own the shares you’re selling. You borrow them from your brokerage, sell them on the open market at the current price, and then wait. If the stock drops, you buy back the same number of shares at the lower price and return them to the lender. The gap between your selling price and your buying price is your profit.
Here’s a simple example. Say you believe a company trading at $50 per share is overvalued. You borrow 100 shares through your broker and sell them, collecting $5,000. A few weeks later, the stock falls to $35. You buy 100 shares for $3,500, return them to the lender, and keep the $1,500 difference (minus fees). If the stock rises to $65 instead, you’d lose $1,500 buying those shares back.
Steps to Open a Short Position
You can’t short sell from a regular brokerage account. You need a margin account, which lets you borrow shares and requires you to maintain a minimum balance as collateral to cover potential losses. Once that’s set up, the process looks like this:
- Find a stock to short. Traders look at financial reports, industry trends, technical indicators, or broader market conditions to identify stocks they believe will decline.
- Locate borrowable shares. Your broker needs to find shares that can be lent to you. Most brokerages handle this automatically, pulling from other clients’ accounts or institutional lenders. Some stocks are easy to borrow, others are not.
- Place the order. On your brokerage platform, you enter a sell order for the stock, specifying it as a short sale. You can use a market order (sell immediately at the current price) or a limit order (sell only if the price hits a level you choose).
- Monitor the position. Once the short is open, you watch the stock. If the price moves against you (goes up), your losses grow in real time, and your broker may require you to add more collateral.
- Close the position. When you’re ready, you enter a buy order for the same number of shares. This “covers” your short, returning the borrowed shares to the lender and locking in your gain or loss.
What It Costs to Short a Stock
Shorting involves more than just the risk of the stock moving against you. There are direct costs that eat into your returns even if the trade goes your way.
The primary cost is the stock loan fee, which is essentially rent for borrowing the shares. For widely available stocks, this fee is small. For hard-to-borrow stocks (ones that many traders want to short or that have limited supply), the fee can be significant. The harder a stock is to borrow, the more you’ll pay.
You also pay interest on the margin balance your broker extends to you. And if the company pays a dividend while you’re holding the short position, you owe that dividend payment to the lender. So shorting a stock that pays regular dividends adds an ongoing cost for as long as you keep the position open.
Why Losses Can Be Unlimited
This is the single most important thing to understand about shorting. When you buy a stock normally, the worst that can happen is the stock falls to zero and you lose 100% of your investment. When you short a stock, there is no ceiling on how high the price can go, which means there is no ceiling on how much you can lose.
If you short a stock at $50 and it climbs to $150, you’ve lost $100 per share, or twice your original position. If it climbs to $500, you’ve lost $450 per share. The stock can keep rising, and your losses keep growing. This asymmetry is why short selling is considered far riskier than buying. Many short sellers use stop-loss orders, which automatically buy back shares if the price hits a certain level, to cap their potential losses.
What a Short Squeeze Is
A short squeeze happens when a heavily shorted stock suddenly rises in price, forcing short sellers to buy back shares to limit their losses. That wave of buying pushes the price even higher, which forces more short sellers to cover, creating a self-reinforcing cycle that can send a stock soaring far beyond what its fundamentals would justify.
The longer it takes for short sellers to close their positions, the longer the price rally can continue. This is why investors pay attention to a metric called “days to cover,” which estimates how many trading days it would take for all short sellers to buy back their shares. The formula is simple: divide the total number of shares currently sold short (called short interest) by the stock’s average daily trading volume. A high days-to-cover ratio suggests it would take a long time for shorts to exit, making a squeeze more likely if the stock starts rising.
How Investors Use Short Interest Data
Even if you never plan to short a stock yourself, short interest data can tell you something useful about market sentiment. A high level of short interest means many traders are betting against a company. That could signal genuine problems with the business, or it could mean the stock is primed for a squeeze if good news arrives.
Traders sometimes buy shares of heavily shorted stocks specifically because they see squeeze potential. If the stock rallies even slightly, the rush of short sellers covering their positions can amplify the move. On the other hand, low short interest generally suggests traders aren’t particularly bearish, though it doesn’t guarantee the stock will rise.
Other Risks Beyond Price Moves
Price going up is the obvious risk, but short sellers face a few others. Your broker can force you to close your position through what’s called a buy-in. This happens when the shares you borrowed become difficult to source and the original lender wants them back. You have no control over the timing, and you may be forced to buy at an unfavorable price.
There’s also regulatory risk. During periods of extreme market stress, regulators have historically imposed temporary bans on short selling in specific sectors or across the broader market to prevent panic selling from accelerating a downturn. If a ban hits while you have an open short position, it can complicate your ability to manage the trade.
Finally, the margin requirements themselves create pressure. If the stock you shorted rises, your broker will require you to deposit additional cash or securities to maintain the minimum collateral level. If you can’t meet that margin call, the broker will close your position automatically, locking in your loss.