This section explains the mechanics of stock trading and lending, detailing how stock lending enables short selling and its implications for market settlement cycles like T+1.
Say you are a big mutual fund and you own 1,000 shares of Stock X and you want to sell. You meet a pension fund that wants to buy 1,000 shares of Stock X, the pension fund comes to your office to negotiate a trade, and you agree on a price of, say, $14 per share. The pension fund reaches into its bag of cash, pulls out $14,000 in crisp $20 bills and hands them to you. You open up your vault, pull out a stock certificate that says "1,000 Shares of Stock X" and hand it to the pension fund. "Pleasure doing business with you," you say; you shake hands with the pension fund and it walks out of your office holding the shares.
This is not quite an accurate description of how you trade stocks in 2024. For instance, in reality, you negotiate this trade anonymously and electronically on the stock exchange, [1] the "stock" consists of an entry in an electronic database rather than paper certificates, and the "$14,000" consists of an entry in a different electronic database. But those distinctions are not particularly important, and let's ignore them for now.
Instead let's just pretend that everything is done face to face with vaults and paper money, and talk about a different complication. That complication is: If you are a big mutual fund in 2024 and you own 1,000 shares of Stock X, you don't just keep the shares in your vault. No, what has actually happened is that, a month ago, a hedge fund came to you and said: "Hey, I hear you have some shares of Stock X sitting in your vault. I would like to borrow those shares from you, for my own purposes." And you sat down with that hedge fund and negotiated a trade — not a stock trade, but a stock lending trade. You didn't sell your stock, but you agreed to lend the hedge fund your stock certificates, and the hedge fund agreed to post some cash collateral to secure the loan, and the hedge fund agreed to pay you a fee — essentially, interest — for borrowing the stock. [2] Also the loan has a term: Maybe you agreed that the hedge fund would return the stock certificates in 90 days, for instance, but much more likely you agreed to "open" term, where the hedge fund can return the shares to you whenever it wants, and you can demand them back whenever you want.
Why did the hedge fund want to borrow your stock? There's really only one possible answer: The hedge fund wanted to short Stock X; it wanted to sell shares of Stock X that it didn't own, betting that the stock would drop and it could buy the shares back cheaper later. To do that, of course, it needed shares of Stock X: In my slightly fanciful world of tangible face-to-face stock trades, a hedge fund can't "sell Stock X" without handing over actual certificates of Stock X. This is where you came in: You loaned the hedge fund some shares of Stock X, the hedge fund sold them, and it hopes to buy them back in the future for cheaper and return them to you to close out the loan.
Why did you agree to lend the hedge fund the shares, if you knew that the hedge fund was betting they'd go down? You own Stock X; you want it to go up; why would you help someone bet against it? Oh, reasons. You might think "this hedge fund is going to short the stock anyway by borrowing it from someone and paying a fee, so I might as well get the fee." You might think "this hedge fund thinks the stock will go down, but it is wrong, and I will profit from its folly." You might think "actually this hedge fund isn't really betting that the stock will go down, but doing some sort of market-neutral or options market-making or convertible arbitrage strategy, so there is nothing offensive about its shorting." You might think "I am actually an index fund paid to track an index, so I don't much care if my stocks go up or down, and getting a little stock-lending income can help me offset my expenses." Doesn't matter; the point is that you were happy to get some stock-lending income by helping a short seller out.
But now you want to sell the stock, and the nice pension fund is sitting in your office with its bag of cash, and you open your vault and there is no stock there. There's a pile of cash (the collateral from the hedge fund), and a little note saying "IOU 1,000 shares of Stock X." And so you turn to the pension fund and say "oh, sorry, I want to sell you this stock, and I own it, but I don't have it right now, can we meet back here in a couple of days and I'll give it to you?"
And the pension fund says "actually that's fine, no problem. In fact, to tell you the truth, I was hoping you'd say that, because I don't have any cash in my bag either. You see, as a pension fund, I have a fiduciary duty to maximize returns, and if I just carried around a bunch of $20 bills in a sack I would not be earning any interest. So in fact I invest all my cash in a money-market fund, which pays a fairly risk-free interest rate, and when I need to buy stock I take cash out of the money-market fund to get the $20 bills to pay for the stock. Right now all that's in the bag is a piece of paper with my money-market fund account number on it. Tell you what, though: You go out and find those stock certificates that you own, and I'll go get cash from my money-market fund, and we'll meet back here in a couple of days and swap."
And so you agree on a trade — a size and price, you sell 1,000 shares of Stock X to the pension fund for $14 per share — and agree to come back in two days to settle the trade, that is, exchange dollars for shares. This is called "T+2 settlement." And then in the intervening two days everyone is busy:
1. You call up the hedge fund and say "Hi, remember those 1,000 shares of Stock X I loaned you? I need them back. Can you come by my office tomorrow and return them?" And the hedge fund says "sure, we agreed to an open-term loan, and I honor my commitments, so I'll be there tomorrow with your shares."
2. But remember, the hedge fund sold your shares! It doesn't have them. So it has to go out and find 1,000 shares of Stock X to return to you. Probably it will call some other investor and say "hey do you have 1,000 shares of Stock X I can borrow," negotiate a new loan, and get the 1,000 shares just in time to meet you at your office tomorrow to return them.
3. But if it can't find a new loan, in the worst case, it will have to go out and buy back the 1,000 shares so it can return them to you. But this is tricky, because what if that trade takes two days to settle? Then the hedge fund won't have the shares in time to return them to you tomorrow!
4. Meanwhile, the pension fund goes to its money market fund manager and says "I need to cash out $14,000 please." And the money market fund manager gives it $14,000 and cancels some of its shares.
5. Where does the money market fund get the $14,000 from? Well, probably it owns a bunch of Treasury bills, and it goes and sells them in the market for cash, and it uses the cash to pay out the pension fund. That trade, too, has to settle: The money market fund has to deliver the bills, and the buyer has to deliver the cash.
And then if all goes well, you meet up two days later and exchange the $20 bills for the stock certificates. But it is not unheard of for all not to go well. You might show up two days later with no stock certificates and say "look, I own that stock, I promise I'm good for it , but what happened is that I lent it out to a hedge fund, and I recalled it, and they couldn't find anyone else to borrow it from, so they had to buy it back in, and they did , they bought the stock from another investor, but the person they bought it from hasn't delivered it yet, but she said that she will tomorrow, and the hedge fund will run it over to my office as soon as they get it, so I should have it by 2 p.m. tomorrow at the latest, so let's meet up then, really sorry for the inconvenience." And the pension fund will be annoyed, but it will also be like "yeah that stuff happens in the stock mar