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What zero borrow means

A stock shows zero borrow when a broker or lender has no shares of it left to lend. Nobody can borrow from that supply to sell short until shares come back. Here is what that does, and does not, tell you.

Short selling runs on borrowed shares

To sell a stock short, a trader sells shares they do not own and buys them back later. The buyer still has to receive real shares, so the short seller’s broker borrows them from a lender, and the short seller pays a borrow fee for as long as the loan stays open.

Regulation SHO makes the borrow a precondition. A broker-dealer may not accept a short sale order, or sell short for itself, unless it has borrowed the shares, arranged to borrow them, or has reasonable grounds to believe they can be borrowed in time for delivery — and has documented that. Market makers doing bona fide market making are exempt. This check is the locate requirement, and it is why availability matters.

What zero borrow means

Shares available to borrow is what a broker or lender reports it can lend right now. Each firm publishes its own figure, so it describes that firm’s supply rather than every share in the market, and the figure is indicative: it can change during the day. At zero, that supply has nothing left, so new short sales cannot be located against it.

Shares come back when short sellers cover and return them, or when holders make more available. They go when new short sellers take them, or when lenders recall them.

Where the borrow fee fits in

The borrow fee — also shown as cost to borrow, or CTB — is the annualised rate a short seller pays to keep the loan open. For most stocks it is small: an SEC staff report put the average securities lending fee at 1.5% a year between 2007 and 2018. It climbs when a stock becomes hard to borrow — low liquidity, heavy demand to borrow, volatility — which is why a stock close to zero availability usually carries a high fee.

Because the rate is annualised, a 100% fee costs a short seller roughly 0.27% of the position’s value for each day the loan stays open.

What zero borrow does not mean

Zero availability stops new borrowing from that supply; it does not recall loans that are already open. What can force an existing short out is a recall: the lender can call its shares back at any time, and if the broker cannot replace them, the position can be bought in — whether or not availability shows zero.

It is not short interest either. Short interest is the total of open short positions that firms report to FINRA twice a month; availability is what is left to lend right now. And it is not a signal by itself: it shows that lending supply ran out, and says nothing about which way the price goes next.

In TickerRoom

The Zero-Borrow Scanner posts the moment a stock’s available shares to borrow reach zero, with the borrow fee and short interest behind it. /borrow-fee shows whether availability comes back.

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