Questions: Short Selling: Mechanics, Costs, and Constraints

Question 1

An investor shorts 100 shares at $50 each. The stock then rises to $200. Which of the following best describes the investor's situation?

• A. The maximum loss is $5,000 (the original proceeds) because you cannot lose more than you initially received
• B. The loss is $15,000 (price gain × shares), and margin requirements may trigger a margin call requiring additional cash
• C. The investor profits because they sold at a price lower than the current market price
• D. The loss is capped at the borrow fee paid to the broker over the holding period

Answer: (B)

The short seller must buy back shares at $200 that were sold at $50 — a loss of $150 per share × 100 shares = $15,000. Unlike a long position where the maximum loss is what you paid, short selling losses are theoretically unlimited because the stock price can rise without bound. Margin requirements compound this: as the stock rises, the short seller must post more collateral, potentially receiving a margin call (demanding additional cash immediately) before the position can be sustained. This asymmetric loss profile distinguishes short selling from all long strategies.

Question 2

Stock X has 30% of its float sold short and shares are hard to borrow. A fundamental analyst concludes the stock is overvalued by 50%. What does short selling theory predict about the stock's market price?

• A. The price will quickly converge to fundamental value as rational arbitrageurs short the stock
• B. The price may remain elevated because high borrow costs and squeeze risk prevent pessimists from expressing their view efficiently
• C. The price will rise further because high short interest signals strong buying demand
• D. The price will fall because existing short sellers' margin calls will force them to dump shares

Answer: (B)

Short selling constraints — high borrow fees, margin requirements, and squeeze risk — prevent pessimistic investors from correcting mispricings. Potential short sellers face borrow costs that eat into profits, capital tied up in margin, and the risk that if the stock rises further they face margin calls before the price reverts. Empirical research confirms that stocks with high borrow costs tend to be overpriced on average, precisely because the mechanism that would correct overvaluation (short selling) is blocked. Market efficiency requires not just smart investors but the ability to act on negative views.

Question 3

A short seller's maximum possible loss is theoretically unlimited, unlike a long investor whose maximum loss is capped at the amount invested.

• T. True
• F. False

Answer: True

A long investor who buys shares at $50 can lose at most $50 per share (if the stock goes to zero). A short seller who sells borrowed shares at $50 must eventually buy them back — and there is no cap on how high the price can go. If the stock rises to $500, the short seller loses $450 per share. This unlimited downside is the defining asymmetry of short selling and the primary reason it requires margin accounts and active position monitoring.

Question 4

A short squeeze occurs when a heavily shorted stock falls sharply, forcing short sellers to close positions and amplifying the decline.

• T. True
• F. False

Answer: False

A short squeeze occurs when a heavily shorted stock *rises* sharply. Rising prices erode short sellers' margin buffers, triggering margin calls that force them to buy shares to close their positions. This buying pressure drives the price even higher, triggering more margin calls on other short sellers — a self-reinforcing cycle. The squeeze is the risk that makes short selling in heavily-shorted, hard-to-borrow names especially dangerous: the worse the trade goes (stock rising), the more capital you are forced to post.

Question 5

Explain the short rebate and borrow fee mechanism. Why does a 'hard-to-borrow' stock create additional risks for short sellers beyond the basic directional bet?

Model answer: When you short a stock, the cash proceeds from the sale sit as collateral; the broker passes most of this back to you as the 'short rebate' (interest on the collateral), minus a 'borrow fee' for lending the shares. For easy-to-borrow stocks, the fee is minimal. For hard-to-borrow stocks (heavily shorted, thinly held), the fee can reach 10–100% annually, directly reducing profits. Beyond cost, hard-to-borrow status signals high short interest, which means elevated squeeze risk — if the stock rises, many short sellers face margin calls simultaneously, creating self-reinforcing buying pressure.

The borrow fee is a continuous drag on the trade: even if you are right about the direction, you can lose money if the convergence to fair value is too slow or the fee too high. Hard-to-borrow status also signals that the market has already 'noticed' the overvaluation — many pessimists are already short — which means squeeze risk is elevated. The combination of high carrying cost and squeeze risk means hard-to-borrow shorts require larger mispricing and faster convergence to be profitable.