Short Selling

Most investors only make money when prices rise. But there’s also the reverse: betting on falling prices. The best-known tool for that is the short sale. It sounds paradoxical – selling something you don’t own – but it’s a standard part of market mechanics. And it carries risks you should understand precisely.

How a short sale works#

A short sale has three steps:

1. Borrow: your broker lends you shares, typically from other clients’ or institutions’ holdings (securities lending).
2. Sell: you sell the borrowed shares in the market and receive the proceeds.
3. Buy back (cover): later you buy the shares back and return them. If the price fell, you keep the difference.

Short sales require a margin account. The broker demands collateral and can issue margin calls if the price moves against you.

The costs#

• Borrow fee: you pay to borrow the shares, usually an annual percentage. For large, easy-to-borrow stocks it’s small; for stocks many want to short (“hard to borrow”), it can reach 20%, 50% or more a year.
• Dividends: if the company pays a dividend while you’re short, you owe it to the lender.
• Recall: the lender can demand the shares back at any time. If your broker can’t find a replacement, you may be forced to cover at a bad moment.

Asymmetric risk#

The key difference from buying a stock lies in how risk is distributed:

And because stock markets rise in the long run, time works against the short seller. Staying short means not only being right but also getting the timing right.

The short squeeze#

When many investors have shorted the same stock and the price suddenly rises, they come under pressure: losses mount, brokers demand collateral, borrow fees climb. To cap their losses they buy back – and exactly that buying pushes the price higher still. This chain reaction is a short squeeze.

Measures of squeeze risk include short interest (shorted shares as a share of the float) and days to cover (how many days of average volume it would take to buy back all short positions).

What short sellers are good for#

Short sellers have a bad reputation because they profit from falling prices. But they serve important functions:

• Price discovery: without short sellers, only optimists could express their views. Overvaluations would persist longer.
• Liquidity: short sellers add supply and make markets more tradable.
• Exposing fraud: specialist short sellers often dig deep into accounts. Short sellers were among the early critics of Enron, Wirecard and others – Germany’s regulator even banned shorting Wirecard in 2019, before the allegations proved true.

Regulation#

In the US, brokers must locate shares to borrow before a short sale; “naked” short selling without a borrow is prohibited. The EU likewise bans uncovered short sales of shares and requires net short positions of 0.1% of a company’s capital to be reported to regulators and 0.5% to be disclosed publicly. In crises, regulators can temporarily ban short selling altogether.

Summary#

A short sale means borrowing shares, selling them and hopefully buying them back cheaper. The gain is capped, the loss theoretically unlimited, and borrow fees and dividends cost money along the way. Short squeezes can make prices explode. Short sellers matter for markets; for most individuals they’re a tool better understood than used.