Introduction to Short Selling: Principles and Mechanisms
Short selling consists of selling financial securities that one does not own, with the objective of buying them back later at a lower price, thus making a profit from the decline in their value. This speculative strategy is used by both retail investors and professionals to hedge against an anticipated drop or to bet on the depreciation of an asset.
In France, the most common instruments to short a stock are Contracts for Difference (CFDs) and the Deferred Settlement Service (SRD). These two mechanisms have distinct modalities, specific risks, as well as a precise regulatory framework defined by the Autorité des Marchés Financiers (AMF).
How to Short a Stock via CFD
CFDs are derivative products that allow taking a short position without owning the underlying security. When an investor opens a short position on a CFD, they commit to paying the difference between the opening price and the closing price of the contract.
Main characteristics of shorting via CFD:
Leverage: generally between 5x and 30x depending on the stock’s volatility, which amplifies both gains and losses.
No physical delivery: the CFD is a purely financial contract; no actual shares are borrowed or sold.
Costs: daily financing fees apply for positions held beyond one day, typically ranging from 0.5% to 1.5% annualized (Bloomberg, 2023).
Accessibility: CFDs are offered by online brokers regulated by the AMF, requiring a dedicated account and knowledge of the risks.
Numerical example: if a stock priced at €100 is short sold via CFD with 10x leverage, a 10% drop in the stock price (to €90) generates a 100% gain on the initial margin, but a 10% rise would result in a total loss of the margin.
Shorting via the Deferred Settlement Service (SRD)
The SRD is a French mechanism allowing the deferral of settlement for stock purchase or sale transactions until the end of the trading month. The SRD also authorizes short selling of stocks listed on Euronext Paris.
Characteristics of shorting via SRD:
Actual borrowing of shares: the financial operator borrows the shares before selling them, implying stricter oversight.
Deferred settlement: payment or delivery of shares occurs at the end of the trading month, offering temporal flexibility.
Costs: financing fees apply, with an average annual rate around 3% according to Banque de France (2023).
Conditions: accessible only to SRD-eligible securities, with leverage limited to 5x.
CFD vs SRD comparison:
Criterion
CFD
SRD
Ownership of shares
No, financial contract
Yes, borrowed shares
Leverage
5x to 30x
Up to 5x
Duration
Unlimited (subject to financing)
End of trading month
Financing costs
0.5% to 1.5% annualized
Approximately 3% annualized
Regulation
AMF + ESMA
AMF + Euronext
Risks Inherent to Short Selling
The major risk of short selling is considered "theoretically unlimited," because the potential loss depends on the rise in the stock price. Unlike a long position, where the maximum loss is the total invested capital (the stock can fall to zero), a shorted stock can see its price soar without limit. For example, a stock at €50 that climbs to €200 generates a 300% loss on the short position.
Other significant risks:
Margin calls: in case of adverse movement, the broker may require immediate additional funds, under penalty of forced position closure.
Recall risk of shares: within the SRD framework, the borrower must return the shares, which may force premature position covering.
High financial costs: accumulated financing fees can heavily weigh on profitability.
Temporary regulatory bans: in periods of extreme volatility, authorities may restrict or suspend short selling.
The Iconic Case of GameStop and Short Squeezes
In January 2021, GameStop (GME) experienced a spectacular "short squeeze." Hedge funds had massively shorted the stock, deemed overvalued. A community of retail investors coordinated via the Reddit forum "r/WallStreetBets" massively bought shares and options to push the price up, forcing short sellers to buy back their positions at high prices, amplifying the rise.
Key figures:
Short interest exceeding 140% of GameStop’s float, an extreme level (Bloomberg, 2021).
The price rose from $20 in early January 2021 to over $480 mid-January, before experiencing high volatility.
Losses estimated in the billions of dollars for hedge funds such as Melvin Capital.
This case illustrates the systemic risk that short selling can induce, especially during periods of high volatility and coordinated investor action.
AMF Regulation on Short Positions in France
The Autorité des Marchés Financiers strictly regulates short selling to ensure market transparency and stability. The main obligations are:
Declaration of net short positions: any actor holding a net short position equal to or exceeding 0.5% of a listed company’s capital must declare it to the AMF (AMF, Regulation 2022).
Temporary bans: during periods of high volatility or crisis (e.g., COVID-19 pandemic in 2020), the AMF may suspend short selling on certain securities.
Prohibited practices: naked short selling is forbidden.
Increased transparency: institutional investors must regularly disclose their positions.
These measures aim to limit excessive risks and prevent market manipulation.
Conclusion and Recommendations for French Investors
Short selling via CFD or SRD is a complex strategy, offering significant profit potential but also theoretically unlimited loss risk. Leverage amplifies these effects, and financing costs must be factored into profitability calculations.
The GameStop case shows that short squeezes can cause extreme and unpredictable movements, underscoring the need for investors to fully master the mechanisms and not expose themselves beyond their risk tolerance.
The AMF regulation imposes strict transparency and limits to protect the market but does not eliminate the inherent risks of this practice.
Verdict: Short selling should be reserved for experienced investors with rigorous risk management and financial capacity to absorb significant losses. For most retail investors, less risky hedging alternatives should be preferred.
Main sources: AMF (2022), Banque de France (2023), Bloomberg (2021-2023), INSEE (general economic data).
