Brokerage Cash Sweep: Where Your Idle Cash Actually Sits

Money sitting uninvested in a brokerage account — after a sale, before a purchase, or as a deliberate reserve — does not stay in the brokerage. Most brokers run a cash sweep: an automatic arrangement that moves idle balances somewhere overnight.

Where it goes determines two things that matter: what you are paid on it, and what happens to it if something fails.

The three destinations

Sweep programmes are not one product. The usual designs:

Bank deposit sweep. Your cash is moved into deposit accounts at one or more partner banks. You become a depositor at those banks, with the broker as intermediary. This is the most common design at large brokers.

Money market fund. Your cash buys shares in a fund holding short-dated instruments. You are a fund investor, not a depositor.

Held at the broker. The cash stays on the broker's own books as a credit balance.

These look identical on your screen — one cash line — and they are legally different in ways that only become visible on a bad day.

Why the destination changes your protection

This is the part worth reading twice, because the protection you have depends on which of the three you are in.

In a bank deposit sweep, deposit insurance applies. In the United States the Federal Deposit Insurance Corporation insures deposits up to a statutory limit per depositor, per insured bank, per ownership category. Because the limit is per bank, a sweep spread across several partner banks can carry more total insurance than a single bank could. That is the main reason multi-bank sweeps exist.

The trap: if you already hold a personal account at one of the partner banks, those balances aggregate for the limit. You can be over the line without ever having chosen that bank.

In a money market fund, deposit insurance does not apply at all. Fund shares are securities. In the United States they fall under the Securities Investor Protection Corporation regime, which protects against the failure of the broker — it does not protect against the fund losing value. A money market fund is designed to be stable, not guaranteed to be.

Held at the broker, you are relying on the broker's own segregation of client assets and on the investor-protection scheme of its jurisdiction. Within the EEA that is the national investor compensation scheme established under the Investor Compensation Schemes Directive; in the UK it is the Financial Services Compensation Scheme.

The rule underneath all three: deposit insurance covers a bank failing, investor protection covers a broker failing, and neither covers an investment falling in value. They are answers to different questions, and they are routinely conflated in marketing copy.

What you are paid, and why it is often low

A broker running a bank sweep earns on the spread between what the partner banks pay and what it passes to you. That spread is a significant revenue line for brokers that advertise zero commissions, which is worth understanding as a matter of business model rather than grievance — the service is being paid for somewhere.

The practical consequence is that a default sweep is frequently not the best available rate for cash you intend to leave alone. Brokers often offer an alternative, opt-in destination that pays differently. It is rarely the default, and switching is usually a setting rather than an account change.

We deliberately publish no rate here. Sweep rates move with central bank policy and change without notice; a number printed in an article is misleading within weeks. Read the current figure on your broker's own disclosure page, where they are obliged to state it.

Questions worth asking your broker

The list of partner banks is the one most people never ask for, and it is the one that determines whether your insurance limit is what you think.

When a sweep is the wrong tool entirely

A sweep is built for cash that is between investments. It is convenient and it is liquid.

For money with a job and a date — an emergency reserve, a deposit for a purchase next year — the question is different, and the answer usually lives outside the brokerage. Our emergency fund guide covers sizing and placement for money that must be there on the worst possible day.

For a longer horizon, holding a large permanent cash balance inside a brokerage is usually an unexamined default rather than a decision. Cash is a position. It should be one you chose.

The one-line summary

Your idle brokerage cash is somewhere specific tonight, earning something specific, protected by a specific scheme. Most investors could not name any of the three. Finding out takes one look at your broker's cash disclosure, and it is the highest-value ten minutes available to anyone holding a meaningful balance.

Nothing here is financial advice. Capital is at risk, and insurance limits and scheme rules vary by jurisdiction — confirm yours with the scheme itself.