Cash sweep accounts: where idle cash goes, what it earns and how it is insured

Money that lands in a brokerage or fintech account and is not invested does not sit still. Each day, the platform moves it, or sweeps it, into a bank deposit, a money market fund or a cash balance at the firm, and that choice decides both what the cash earns and which protection applies. The SEC notes that many firms make a bank sweep the default. That can be fine for a few days between trades, and expensive for money that stays for months. This guide explains how sweep programs work, what they paid in late October 2026, how pass-through insurance applies and what the 2024 Synapse collapse showed about the plumbing.

What is a cash sweep account?

A cash sweep account is the arrangement a broker or app uses to park your uninvested cash automatically, usually in partner bank deposits or a money market fund.

The SEC's investor bulletin describes three common options:

• Bank sweep. Cash goes into deposit accounts at one or more banks, which may be affiliated with the firm. It earns a variable rate and is FDIC insured at each bank within the limits.
• Money market fund sweep. Cash buys shares of a money market fund, which pays dividends that track short-term rates. Fund shares are not FDIC insured, but SIPC protects them as securities if the broker fails.
• Free credit balance. Cash simply stays at the firm, which may or may not pay interest, and is generally covered by SIPC.

Uninvested cash comes from deposits, dividends, interest and sale proceeds. FINRA observes that many full-service brokerage firms offer only a bank sweep, and that cash meant as a short stop often stays much longer than planned.

How do sweep programs move cash to partner banks?

Each business day, the firm totals customers' uninvested cash and moves it into pooled custodial deposit accounts at its program banks, keeping a ledger of who owns what.

At each bank, the money usually sits in an omnibus account titled to show it is held for the benefit of the firm's customers. The firm's own records, not the bank's, typically track each customer's share. Multi-bank programs fill banks in a priority order, placing up to an insured amount per customer at each before moving to the next. One disclosure from October 2026 lists 19 program banks per region, with the order set by the customer's state of residence, plus a separate short list of excess banks. Another advertises up to $2.5 million of FDIC coverage per depositor.

Fintech apps add a layer. The app collects your money, a middleware company may keep the ledger, and one or more partner banks hold the pooled deposits. The FDIC is blunt about this structure: non-bank companies are never FDIC insured, and money sent to one is not eligible until it has actually been deposited at an insured bank and other conditions are met.

What do sweep accounts pay compared with money market funds?

Bank sweep rates are often a small fraction of money market fund yields and Treasury bill rates, especially on smaller balances.

The table compares published rates from two multi-bank sweep programs with alternatives available on the same dates.

For context, the FDIC's national average savings rate was 0.38% (FDIC, as of Nov 1, 2026), and the federal funds target range was 3.75% to 4.00%. The regulators have flagged the same pattern. FINRA has said the difference between sweep, money market fund and free credit balance rates can be as much as 5 percent, particularly when rates are higher. In January 2025, the SEC settled charges with three advisory firms at two large brokerage groups, which paid $60 million in combined penalties; it found that bank sweeps were the only option for most of their advisory clients and that the yield gap with other sweep options at times grew to almost 4 percent.

Where does the difference go? One firm's disclosure gives a worked illustration: if a program bank pays the firm the federal funds rate plus 0.15%, and that rate is 4.00%, the firm receives 4.15% on the swept cash. If it credits the customer 0.05%, it keeps 4.10% as compensation, out of which it pays its vendors and the costs of running the program. On $100,000, that is $4,150 a year paid by the bank, $50 to the customer and $4,100 to the firm.

Fees can make the arithmetic worse. The SEC's bulletin warns that asset-based fees may apply to cash too. A 1% advisory fee on $100,000 swept at 0.27%, program A's rate for that tier, leaves the customer about $730 a year worse off after fees. How money market funds and bills compare in detail is covered in how money market funds work and T-bills vs money market funds, and the Treasury bill calculator shows what a bill purchase would earn.

How does pass-through FDIC insurance apply to sweep accounts?

Swept deposits are insured as if you had deposited them yourself, but only if three conditions in the FDIC's pass-through rules are met at the moment a bank fails.

1. The bank's account records must disclose the custodial relationship, usually through a title showing the account is held as agent or for the benefit of others.
2. Each owner's identity and share must be ascertainable from the bank's records or from records kept by the platform or its recordkeeper.
3. The customers, not the platform, must actually own the funds under the account agreements.

Two practical consequences follow. Swept balances are added to any deposits you already hold at the same bank in the same ownership category, so a program bank where you also bank directly can push you over the limit; ask to exclude it. And the FDIC pays a fiduciary's customers through the fiduciary, relying on its records. Coverage protects against a program bank failing. It does nothing if the broker, the app or its ledger provider fails, which is the gap FDIC vs SIPC maps in full. The limits themselves are explained in FDIC insurance explained.

What is the FDIC's custodial account recordkeeping rule?

It is a proposal, published on October 2, 2024, that would make banks keep reconciled records of who owns the money in pooled custodial accounts with transactional features.

The proposal came about five months after Synapse's bankruptcy and targets the same weakness. It would apply to custodial deposit accounts with transactional features, the type used by payment apps and fintech programs, and would require the bank to maintain records identifying each beneficial owner, the balance attributable to each and the ownership category. A bank could rely on a third party's records only with direct, continuous and unrestricted access, including if that third party went bankrupt. Records would have to be reconciled at least as of the close of each business day, and banks would file annual certifications and reports. The FDIC estimated that between 600 and 1,100 banks hold such accounts.

Its status: proposed in October 2024 and still not final; the latest Unified Agenda lists it as a long-term action with no date set for a final rule (Office of Information and Regulatory Affairs (Reginfo.gov), as of Nov 1, 2026). Until a final rule takes effect, the protection a sweep customer relies on rests on the existing pass-through rules and on the platform's own records.

What happened in the 2024 Synapse case?

Synapse, a middleware firm that connected fintech apps to partner banks, filed for chapter 11 bankruptcy on April 22, 2024, and its records did not match the banks'.

According to the CFPB's complaint, the partner banks found that the funds they held for consumers were $60 million to $90 million less than Synapse's records showed. Consumers had no access to their money for weeks or months while the banks reconciled the records, and many have not received their full balances. The CFPB alleged that Synapse failed to keep adequate records of where consumers' funds were and to make sure they matched the banks' records.

The court entered a judgment on September 12, 2025, that included a $1 civil penalty, which made the harmed consumers eligible for the CFPB's Civil Penalty Fund. The Bureau has since allocated about $55.2 million from that fund for Synapse victims, in two allocations of about $46.2 million in November 2025 and about $9.0 million in May 2026. There is no application process. Separately, the Federal Reserve took enforcement action in June 2024 against one of Synapse's partner banks over weaknesses in its fintech partnerships.

The lesson for depositors is specific. FDIC insurance never came into play, because no bank failed. Most of the money sat at insured banks; the problem was matching it to its owners, and part of it could not be found.

Questions to ask about any sweep program

These questions come straight from what regulators flag and what went wrong at Synapse.

If the answers point to a low rate on cash you will not need for months, Treasury bills are one alternative that does not depend on deposit insurance.

What are the risks of leaving cash in a sweep account?

The main risk is cost rather than safety: a low sweep rate gives up income every day, while the safety risks come from records and limits, not the banks.

• Yield drag. At 0.03% to 0.16%, a sweep earns a fraction of what bills or money funds paid in late October 2026; the compound interest calculator shows how that gap compounds.
• Fees on cash. Asset-based fees charged on swept cash can turn a positive rate into a net loss.
• Coverage overlap. Swept balances add to your direct deposits at the same bank.
• Excess banks. Some programs place balances beyond their insured capacity at excess banks, where the amount above the limit is uninsured; the disclosure says how yours works.
• Recordkeeping failure. If the firm or its ledger provider fails, access can freeze while records are rebuilt, as Synapse showed.
• Program changes. Firms can change rates, banks or default options with notice, and cash left on autopilot follows the change.
• Money fund sweeps carry their own risk. They are not insured, and a fund may charge a discretionary fee if its board decides that is in the fund's best interest.

None of this argues against sweeps as a parking spot between trades. It argues for checking the rate tier, the bank list and the records arrangement before cash sits there for long. For other places to hold cash, see how high-yield savings accounts work, how to insure more than $250,000 and the safe investments hub.