What is naked shorting, and what is a fail-to-deliver?

Few topics in markets generate more heat and less mechanical clarity. The concepts themselves are narrow and precise, so let us keep them that way.

Covered versus naked

Every sale must be delivered on settlement date — T+1 in the US and several other major markets since 2024, T+2 in others.

A covered short has located and borrowed the shares. On settlement day they are delivered. The buyer receives real shares.
A naked short sells without having arranged the borrow. On settlement day there is nothing to deliver.

When delivery does not happen, the result is a fail-to-deliver (FTD): an open obligation recorded in the clearing system, marked against the failing party and margined until it is resolved.

What a fail actually is, and is not

Most fails are operational, not strategic. A recall unwound at the wrong moment; a delivery arrived late from three links up the chain; an instruction mismatched; a corporate action confused a settlement. Fails occur on long sales too. A background level of fails exists in every market every day and means nothing.

What is different is a large, persistent fail pattern in a single security. That is the signature the rules are built to catch, because a naked short that never delivers has, in effect, sold shares without any supply constraint at all — the one hard limit on short selling is the number of shares that can actually be borrowed.

Why the buyer's position matters

The buyer paid and did not receive. Clearing systems manage the credit risk with margin against the failing party, but the buyer's account does not hold the shares. Depending on the market, their voting and corporate-action rights may be affected until delivery occurs. That is the concrete harm the architecture is designed to prevent.

The regulatory architecture, generically

Rules differ by jurisdiction and change over time, so what follows is the shape common to most major markets rather than any specific rulebook. Nothing here is jurisdiction-specific guidance.

Locate requirement. Before accepting a short-sale order, a broker must have reasonable grounds to believe the security can be borrowed and delivered on time. This is the front door.
Order marking. Sell orders are marked long or short, so short-sale activity is measurable rather than inferred.
Close-out requirements. Fails persisting beyond a set number of settlement days trigger a mandatory buy-in. Further short sales in that security may then require a pre-borrow — an actual struck loan — rather than a locate.
Threshold or watch lists. Securities with fails above a threshold for several consecutive days are published, which is itself a supervisory tool.
Price tests and circuit breakers. Some markets restrict short sales at or below the prevailing bid after a large intraday decline, so shorts cannot press a falling market.
Disclosure regimes. Net short positions above a threshold must be reported to the regulator, and above a higher threshold are often published by name.
Market-maker treatment. Bona-fide market making has historically carried narrower obligations in some markets, on the grounds that a market maker's short is a by-product of quoting both sides rather than a directional position. This exemption is a recurring subject of debate.

The point of the locate rule, in one sentence

Delivery is what makes a sale a sale. The locate requirement exists so that the number of shares that can be sold short is tethered to the number of shares that actually exist and can be borrowed. Everything else in the architecture is enforcement of that one idea.

Try it now

Find out whether your market settles equities at T+1 or T+2 today — several major markets changed in 2024, and more are scheduled to.
Check whether your market's regulator or exchange publishes a fails or threshold securities list, and look at how many names are on it. It is usually a short list.
Look for the public net short position disclosure register if your market has one. Note the disclosure threshold, and how few positions are large enough to appear.