Diversifying across brokers is rational. The risk of losing your assets is very small, but not zero. Also, peace of mind is very important.
I know all the theory about how funds are not owned by the broker, so even if the broker goes bust the investor will still be the beneficial owner, and it all makes perfect sense. But I can still think of several things that could go wrong. The extra hassle of having more than one brokerage account is not a large cost to mitigate the risk (even if the risk is small).
Please tell us how a brokerage can go bust and you lose your bonds/stocks/mutual funds/ETFs during the meltdown. It is in your name, that's why they call it a security.
Now cash sitting at the broker is a different story. But, the positions are yours and yours only.
Okey-dokey. There are a number of scenarios I can think of off the top of my head which are very unlikely but not impossible. They fall broadly into two categories: fraud or incompetence (and most likely both). Regulation and auditing helps mitigate the risk, but we know from Lehman Brothers, Madoff, Enron, Worldcom, Wirecard, Barings Bank, Mirror Group Newspapers, etc, that things go wrong.
Just for fun, let’s say you have an ETF (VTI is popular in these parts, so let’s go with that). Most brokers pool all of the same securities in one nominee account. They then report to their clients the securities that are owned by each of them (what could go wrong, right?).
Scenario 1: Fraud. The broker takes your money and does not buy VTI, but tells you he has. You have a reassuring statement from the broker, and only find out there are no securities when the broker runs out of cash and gets caught out when it can’t pay. That’s basically a Bernie Madoff situation (the former Chairman of NASDAQ and survivor, lest we forget, of multiple SEC investigations).
Scenario 2: Incompetence. A rapidly-growing broker does not invest enough in its IT systems and controls. The pool of VTI nominee accounts starts to deviate from the total holdings of clients. No one knows why. Broker is on the hook for the difference. Key IT staff leave. Broker goes bust. Administrators (very expensive Big 4 firm, who of course get paid before anyone else) some in to sort out the mess. In a few years you get back part of your assets from what they could salvage. Something close to this scenario happened in the 1960s.
Scenario 3. “My broker doesn’t pool my assets. I pay a little more so my VTI are separately ring-fenced.” Smart move, right? Maybe. But what if the broker doesn’t actually do what they say? “Well, due to administrative reasons, we temporarily pooled all assets” say the brokers. You may not think you have counterparty risk because you are the beneficial owner. But perhaps you have a counterparty risk after all, just not the one you thought you had.
Scenario 4: Stock lending goes wrong. There are all sorts of shenanigans around this. Brokers lend your VTI to short sellers for a fee. The broker lends only against other securities (like bonds). Let’s say the borrower does not return the VTI. Meanwhile the bond has lost value (maybe due to default). Or perhaps the broker never took any security. Can the broker make up the loss?
So, there are just a few. I haven’t even started on rogue employees, and there are other “Black Swans” out there too, of course. The reality is that where humans are involved there are going to be mistakes and perhaps dishonesty. You only have to go back to recent history of the Global Financial Crisis to see that. A whole industry convinced itself it was fine to package subprime mortgages into securities which S&P and Moody’s then rated as AAA. UBS alone (then the world’s biggest wealth manager) lost $40 billion on its own account, plus what its clients lost. Screw-ups happen.
Don’t have nightmares, kids. As I said, very unlikely to happen. But the risk is not zero. The decision on diversifying across brokers is really down to the individual.