Securities Lending Is Where Short Selling Gets Its Shares
A short seller must deliver stock they do not own, so they borrow it. The lending market that supplies them is large, quiet, and a meaningful source of income for long term holders.
The Mechanism
A short seller sells shares they do not own and must deliver them at settlement. To do that they borrow the shares from a holder.
The borrower posts collateral, typically cash or high quality securities worth slightly more than the shares, and pays a fee. The lender keeps the fee and retains economic exposure to the stock, since the borrower must return equivalent shares and compensate for any dividends.
The lender still has the economic position. What they give up is the voting right, which transfers with the shares, and that transfer happens quietly at enormous scale.
Who Lends
| Lender | Motivation |
|---|---|
| Index funds | Fee income offsets expense ratio |
| Pension funds | Incremental return on long term holdings |
| Insurers | Yield on stable portfolios |
| Custodians on behalf of clients | Share of the fee |
Index funds are the most significant source. A fund holding a security permanently has no reason not to lend it, and the resulting income is a genuine contributor to why some index funds can charge almost nothing. Part of the fee is retained by the fund manager and part passed to investors, and the split varies considerably.
The Fee Tells You Something
Borrowing fees vary enormously. Widely held large companies with plenty of available supply cost almost nothing to borrow.
Securities that are heavily shorted, or where the available supply is limited, become hard to borrow and command high fees, occasionally very high ones.
The fee is therefore a market price for the difficulty of shorting a security, and it is watched as a sentiment indicator. A rising borrow cost indicates increasing short demand or shrinking supply, and it directly reduces the profitability of holding the short.
Recall Risk
The lender can generally demand the shares back at any time, for example to vote them or because they sold the position.
If the borrower cannot source replacement shares, the position is bought in: closed at the prevailing price whether or not the short seller wants to close it.
This is the mechanism underneath a short squeeze. Rising prices prompt lenders to recall and make borrowing more expensive, forcing shorts to cover, which pushes the price higher, which forces more covering.
The short seller therefore faces a risk that has nothing to do with whether their analysis is correct. Being right eventually is worthless if the position is closed for you first.
The Voting Question
Because voting rights transfer with lent shares, a fund that has lent stock cannot vote it unless it recalls first.
This creates a genuine tension between generating lending income and exercising stewardship responsibilities, particularly for funds that publicly emphasise governance engagement. Most large lenders recall shares ahead of significant votes, which is a cost they accept.
The more serious concern is empty voting: borrowing shares specifically to acquire votes without economic exposure, which allows someone to influence an outcome they have no financial stake in.
The Risks in the Chain
The lender faces borrower default, mitigated by collateral marked daily. Where cash collateral is reinvested, the lender takes reinvestment risk, which produced substantial losses in 2008 for programmes that had reached for yield in what was supposed to be the safe part of the arrangement.
That episode is the important one for anyone assessing a lending programme. The lending itself was not the problem. What was done with the collateral was.
The Bottom Line
Securities lending supplies the shares that short selling requires, earning fees for long term holders and helping subsidise low cost index funds. Borrow fees price how difficult a security is to short, recall risk is what makes squeezes possible, and voting rights transfer with the shares. The historic losses in this activity came from reinvesting cash collateral rather than from the lending.