Where to Park Cash in Your Brokerage Account?

Uninvested cash in a brokerage account has five reasonable homes: the broker’s built-in sweep, a money market mutual fund, Treasury bills bought directly, an ultra-short government bond ETF, or a brokered certificate of deposit. Deciding where to park cash in a brokerage account comes down to when you’ll need the money, how much you’re holding, and whether your state income tax rate makes Treasury interest more valuable than it looks on paper. The yield gap between the worst and best choice can exceed three percentage points, so the decision is worth a few minutes.1FDIC.gov. Deposit Insurance At A Glance

The Default Sweep Is Rarely the Best Answer

Every major brokerage automatically moves uninvested cash into a sweep vehicle overnight. When a dividend lands or a trade settles, the proceeds start earning something without any action on your part. That is the appeal, and for very small balances it’s enough.

The problem is the rate. As of early 2026, one major firm’s default bank sweep pays 0.01% while a government money market fund on the same platform yields over 3%. On a six-figure cash balance that gap is thousands of dollars a year. Some brokers let you switch the sweep destination to a money market fund in a single click; others keep the low-yielding bank sweep as the only automatic option and expect you to place a manual buy order into a fund.

Sweeps that route cash to partner banks carry FDIC insurance up to $250,000 per depositor at each participating bank, and a broker using many partner banks can extend that coverage across a much larger balance.1FDIC.gov. Deposit Insurance At A Glance Sweeps into a money market fund fall under SIPC instead, which covers up to $500,000 total with a $250,000 sublimit for cash and only applies if the brokerage itself fails.2SIPC. What SIPC Protects

Money Market Mutual Funds

Money market funds are the most common upgrade from a low-paying sweep. They hold short-term, high-quality debt and aim to keep a stable share price of $1.00. The SEC regulates them under Rule 2a-7, which caps credit risk, maturity, and concentration.

Government money market funds invest almost entirely in Treasury securities and repurchase agreements backed by government debt, and they maintain a stable $1.00 NAV. Retail prime funds, open only to individual investors, also hold a stable NAV. Institutional prime and institutional tax-exempt funds price to four decimal places and can drift slightly.3U.S. Securities and Exchange Commission. Money Market Fund Reforms Final Rule For most individual investors parking cash, a government or retail prime fund is the straightforward pick.

Municipal money market funds hold short-term state and local government debt, and their dividends may be exempt from federal income tax and sometimes from your home state’s tax. Pre-tax yields are lower, so these funds tend to work only for investors in the top brackets. Dividends are typically paid monthly and can be reinvested automatically or swept back to your core cash.

Treasury Bills

Buying T-bills directly gives you a government obligation with no credit risk and a real tax advantage. Bills are sold at a discount and pay their face value at maturity, with the difference as your return. Available maturities are 4, 8, 13, 26, and 52 weeks, which lets you match the bill to when you’ll actually need the cash.4TreasuryDirect. General Auction Timing

T-bill interest is subject to federal income tax but exempt from all state and local income taxes.5Internal Revenue Service. Topic no. 403, Interest Received In a high-tax state, that exemption can push a T-bill’s after-tax return above a money market fund with a higher headline yield. As of early 2026, T-bill coupon-equivalent yields ran roughly 3.6% to 3.7% across maturities.6U.S. Department of the Treasury. Daily Treasury Bill Rates

The minimum purchase is $100, with additional amounts in $100 increments.7TreasuryDirect. Treasury Bills You can buy at auction or on the secondary market through your brokerage, or directly from TreasuryDirect.

Building a T-Bill Ladder

A ladder spreads cash across bills that mature at staggered intervals. Split $40,000 into four purchases of 4-week, 13-week, 26-week, and 52-week bills, and as each one matures you either spend the proceeds or roll them into a new bill at the longest rung. You get regular access to a portion of your cash while the rest keeps earning. Both TreasuryDirect and many brokerages allow automatic reinvestment at maturity, which keeps the ladder running without manual effort.8TreasuryDirect. Redeem/Reinvest Treasury Bills

Ultra-Short Government Bond ETFs

When you want to move in and out of cash during the trading day, an ultra-short government bond ETF is hard to beat. These funds hold Treasury securities with maturities under one year and trade on exchanges like stocks, so you can buy or sell any time the market is open. Money market funds price only at the end of the day.

Intraday flexibility comes with some cost. Expense ratios in this category run around 0.15% annually.9BlackRock. iShares 0-1 Year Treasury Bond ETF Every trade also crosses a bid-ask spread, usually a penny or two per share on the most liquid funds, which money market funds don’t impose. Most brokerages have dropped ETF trading commissions.

These ETFs also work efficiently as margin collateral. Under FINRA Rule 4210, government obligations with less than one year to maturity require only a 1% maintenance margin, compared with 25% for common stocks.10FINRA.org. FINRA Rule 4210 – Margin Requirements Parking cash here frees up far more buying power than holding the same value in equities.

Because these ETFs hold Treasury securities, their income distributions generally qualify for the same state and local tax exemption as T-bills held directly. Check the prospectus, since a fund holding some non-government securities may not pass through the full exemption.

Brokered Certificates of Deposit

A brokered CD locks in a fixed rate for a set term, purchased through your brokerage rather than a bank. The big structural difference from a bank CD is what happens if you need out early. Bank CDs charge an early withdrawal penalty. Brokered CDs don’t allow early withdrawal at all. Your only exit before maturity is selling on the secondary market at whatever price the current rate environment produces.

If rates have risen since you bought, new CDs pay more and yours sells at a discount. If rates have fallen, yours is more valuable and can sell at a premium. Longer terms are more sensitive to rate moves. For cash you might actually need on short notice, that price risk is a real problem. For money you’re confident stays put, the fixed rate and simplicity are the whole point.

Each brokered CD carries FDIC insurance up to $250,000 per depositor at the issuing bank.1FDIC.gov. Deposit Insurance At A Glance Because a brokerage can source CDs from many different banks, a large cash position can be spread across issuers and stay fully insured. Fees are typically built into the yield rather than charged separately.

How Taxes Change the Comparison

Interest from sweep accounts, money market funds, and CDs is taxed as ordinary income at your federal rate. Money market fund payouts are labeled “dividends” on your 1099 but taxed as interest.5Internal Revenue Service. Topic no. 403, Interest Received For 2026, federal rates range from 10% to 37% depending on income and filing status.11Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026, Including Amendments From the One, Big, Beautiful Bill

Treasury bills and ultra-short Treasury ETFs holding only government securities avoid state and local income tax.5Internal Revenue Service. Topic no. 403, Interest Received Run the numbers before assuming the highest headline yield wins. In a state with a 10% income tax, a money market fund at 4% and a T-bill at 3.8% deliver roughly the same after-tax return, because the T-bill escapes the state layer entirely.

Municipal money market funds flip the equation the other way: dividends may be exempt from federal tax, and from your state’s tax if the underlying debt is issued in your home state. Pre-tax yields are lower, so the benefit concentrates in the highest brackets.

Matching the Choice to Your Timeline

The right parking spot depends mostly on when you’ll need the money and how much effort you want to put into managing it.

  • Cash you may deploy any day. A money market fund sweep or a government money market fund gives you same-day or next-day purchasing power with minimal effort. If your broker’s default sweep pays near zero, manually switching to a higher-yielding fund is the single most valuable move.
  • Money needed in one to six months. T-bills matched to your timeline pay a competitive yield with a state tax advantage and no credit risk. A short ladder adds flexibility when you’re unsure of the exact date.
  • Intraday flexibility with yield. An ultra-short Treasury ETF lets you sell during market hours and doubles as efficient margin collateral. The bid-ask spread makes it slightly costlier than a money market fund for cash that sits still.
  • Money you won’t touch for six to twelve months or more. A brokered CD locks in a rate and takes the decision off your plate. Just be sure you can hold to maturity, because selling early in a rising-rate market means realizing a loss.

Combining two or three of these vehicles is often smarter than picking one. A core money market fund position for immediate liquidity, a T-bill ladder for the bulk of reserves, and a brokered CD for money that won’t move gives you yield, flexibility, and insurance coverage working together.