Money Market Funds vs High-Yield Savings vs T-Bills: Where to Park Cash as the Fed Hikes

Key Takeaway

Cash is earning real money again, and the Federal Reserve may be about to make it earn a little more. The Fed lifted its federal funds target range to 3.75%–4.00% in September 2026, held it there on October 28, and markets are now pricing a high probability of another quarter-point hike at the December 8–9 meeting after the October consumer price index showed core prices rising 0.3% for a third straight month, according to the Bureau of Labor Statistics. Against that backdrop, the three most popular places to park cash are paying broadly similar rates but behave very differently. The U.S. Treasury's daily bill rates put the 13-week bill at a 4.23% coupon-equivalent yield on November 13, 2026, Crane Data's Crane 100 money fund index showed an average 7-day yield of 3.74% on November 14, and the best online savings accounts listed by Bankrate in mid-November advertised APYs in the low-4% range. The FDIC's national average savings rate, by contrast, was just 0.38% as of October 19.

That spread between the best and the average is the first lesson. Many investors are still leaving cash in accounts that pay almost nothing while inflation ran at 3.7% year over year in September, the latest 12-month figure BLS has published. The second lesson is that "money market fund vs high-yield savings vs T-bills" is not really a contest about yield. In a rising-rate environment the differences that matter are how quickly each option resets to higher rates, how it is taxed, what protects your principal, and how fast you can get the money out when the stock market hands you an opportunity.

This guide compares money market funds, high-yield savings accounts, and Treasury bills through the lens of a Fed that is hiking rather than cutting, explains the tax and safety rules that change the real return, and shows how to build a simple cash plan for emergencies, near-term goals, and dry powder for stocks. Rates are as of November 13–14, 2026 (America/New_York) unless noted. Market-implied odds are projections, advertised APYs change frequently, and nothing here is personalized investment advice.

Why Cash Strategy Matters More When the Fed Is Hiking

The return of a positive real yield, barely

For most of the 2010s, cash was a drag on any portfolio. Savings accounts paid fractions of a percent, Treasury bills yielded close to zero, and holding cash meant losing purchasing power almost guaranteed. The situation today is different, but less generous than headlines suggest. With September headline CPI at 3.7% year over year according to BLS, a 13-week bill at about 4.2% delivers a real yield of roughly half a percentage point before taxes. A money market fund yielding 3.74% is essentially treading water in real terms, and the 0.38% national savings average is losing more than three points a year to inflation.

One data wrinkle is worth knowing. BLS said it cannot publish 12-month percent changes for October 2026 CPI because October 2025 prices were never collected during the 2025 government shutdown. The monthly numbers are still clear, though: headline CPI rose 0.4% and core rose 0.3% in October. Those readings are why the Fed turned hawkish, and they are why cash savers should think about real, after-tax returns rather than the headline rate on a bank's homepage.

Rate hikes reach each cash product at a different speed

When the Fed raises rates, Treasury bills reprice almost immediately because they are auctioned every week and trade continuously. In fact, bills often move before the Fed does. On November 13 the 26-week bill yielded 4.47% on a coupon-equivalent basis, well above the 4.02% on the 4-week bill, a slope that suggests the market already expects higher short-term rates in the months ahead.

Money market funds follow with a lag because they hold a portfolio of short-term securities that mature and roll over gradually. Crane Data's index shows the pattern clearly: the Crane 100 average yield rose from 3.51% at the end of August to 3.67% at the end of September and 3.75% at the end of October as the September hike worked through fund portfolios. High-yield savings accounts are the least predictable. Banks set those rates at their own discretion, and they tend to raise them slowly and cut them quickly, a habit economists call low deposit beta.

Money Market Funds Explained

What you actually own

A money market fund is a mutual fund, not a bank account. It pools investor money and buys very short-term, high-quality debt such as Treasury bills, repurchase agreements, and, in prime funds, commercial paper and certificates of deposit issued by corporations and banks. The fund aims to keep a stable $1.00 share price, and the yield you earn is the income from that portfolio minus the fund's expenses.

Investors have embraced the structure. The Investment Company Institute reported total money market fund assets of about $7.98 trillion for the week ended November 11, 2026, after a record of roughly $8.02 trillion the week before. Government funds dominate at about $6.59 trillion, compared with about $1.23 trillion in prime funds and about $160 billion in tax-exempt funds. Crane Data, which tracks a broader universe, puts the total even higher at about $8.36 trillion at the end of October, so it matters which source you cite.

Government, prime, and tax-exempt funds

Government money market funds invest almost entirely in Treasury securities, government agency debt, and repurchase agreements backed by them. They are the default sweep option at many brokerages and the safest flavor of the product. Treasury-only funds go a step further and can pass through income that is exempt from state and local income tax, which matters for investors in high-tax states. Prime funds add some corporate and bank credit risk for a slightly higher yield, and tax-exempt funds buy short-term municipal debt for top-bracket investors.

The safety rules changed after 2023

Money market funds are not FDIC insured, and the FDIC states explicitly that mutual funds, including money market funds, are not covered even when bought through a bank. Their protection comes from regulation instead. In July 2023 the Securities and Exchange Commission adopted reforms that removed the ability of funds to impose redemption gates, raised minimum daily and weekly liquidity requirements to 25% and 50% of assets, and required institutional prime and institutional tax-exempt funds to charge a liquidity fee when daily net redemptions exceed 5%. Retail government funds, the kind most individual investors use, are not subject to that mandatory fee.

If your fund is held at a brokerage, SIPC coverage protects up to $500,000, including $250,000 for cash, if the brokerage itself fails. SIPC is clear, however, that it does not protect against a decline in the value of your securities. The practical takeaway is that a retail government money market fund is a very low-risk vehicle, but its safety comes from what it owns and how it is regulated, not from a federal guarantee.

High-Yield Savings Accounts Explained

The appeal is simplicity and insurance

A high-yield savings account is a deposit at a bank, usually an online bank, that pays far more than the branch-based average. Deposits are covered by FDIC insurance up to $250,000 per depositor, per insured bank, for each account ownership category, which means a joint account and an individual account at the same bank can each be insured separately. Money moves to and from checking within a day or two, there is no share price, and there is nothing to sell.

That simplicity is why high-yield savings remains the natural home for an emergency fund. When a car breaks down or a job ends, nobody wants to think about settlement dates or fund liquidity rules. Bankrate's mid-November 2026 listings showed leading accounts advertising APYs of roughly 4.1% to 4.35%, which is competitive with money funds and not far behind short-term bills.

The catch is that the bank sets the rate

The rate on a savings account is not tied to any market benchmark. Banks raise rates to attract deposits and lower them when they have enough, and promotional rates frequently come with balance minimums, tiers, or limits on who can open the account. Some of the highest advertised rates in November require minimum balances, and at least one leading offer was limited to residents of a single state.

Treasury Bills Explained

Direct lending to the U.S. government

Treasury bills are short-term debt issued by the U.S. Treasury with maturities of four to 52 weeks. They are sold at a discount to face value, and the difference between what you pay and what you receive at maturity is your interest. Bills are backed by the full faith and credit of the U.S. government, and because they are auctioned weekly, investors can buy them directly through TreasuryDirect or through almost any brokerage account.

On November 13, 2026, Treasury's daily bill rate table showed the 4-week bill at a 4.02% coupon-equivalent yield, the 13-week bill at 4.23%, and the 26-week bill at 4.47%. Those are the highest yields of the three cash options discussed here, and unlike a savings account, the rate is locked in until maturity the moment you buy.

The state tax advantage

TreasuryDirect states that interest on Treasury bills is subject to federal income tax but not to state or local income taxes. For an investor in a state with a 9% or 10% top income tax rate, that exemption can be worth several tenths of a percentage point of yield. A 4.2% bill can be equivalent to a fully taxable yield in the mid-4% range for a high-bracket resident of California or New York, which widens its advantage over a high-yield savings account whose interest is taxable at every level.

Comparing the Three Side by Side

Yield, protection, and access at a glance

The cleanest way to compare the options is to line up the features that actually change your outcome. The figures below reflect the sources and dates cited above and will change as the Fed moves.

• Treasury bills: about 4.0% to 4.5% coupon-equivalent depending on maturity (Treasury, November 13); backed by the U.S. government; exempt from state and local income tax; rate locked until maturity; sellable before maturity at market prices.
• Money market funds: about 3.7% average 7-day yield (Crane 100, November 14); not FDIC insured but regulated by the SEC and typically invested in government securities; yield resets gradually; usually same-day or next-day liquidity.
• High-yield savings accounts: top advertised APYs around 4.1% to 4.35% (Bankrate listings, mid-November); FDIC insured up to $250,000 per depositor, per bank, per ownership category; rate set at the bank's discretion; fastest and simplest access.

After-tax yield is the number that matters

Advertised yields are pre-tax, and the tax treatment can easily flip the ranking. Interest from savings accounts and most money market funds is taxed as ordinary income at the federal, state, and local level. Treasury bill interest skips state and local tax, and municipal money funds can skip federal tax as well. An investor in a no-income-tax state may reasonably prefer a top savings account for its simplicity, while a high earner in a high-tax state may find that bills or a Treasury-only fund win comfortably.

A quick calculation is worth doing once. Multiply each yield by one minus your combined marginal tax rate on that type of income, then compare the results with your inflation expectation. With September inflation at 3.7%, after-tax real returns on cash are close to zero for many savers. That is not a reason to avoid cash, but it is a reason not to treat it as a long-term growth asset.

The hidden cost of the default option

The most expensive cash decision is usually the one nobody made. Brokerage sweep accounts, which automatically park uninvested cash, sometimes pay far less than the brokerage's own money market funds. Bank checking and traditional savings accounts often pay a fraction of a percent. Moving idle cash from a 0.4% account to a 4% option on a $50,000 balance adds roughly $1,800 a year in interest before tax, a meaningful sum for a few minutes of paperwork.

How a December Rate Hike Changes the Math

Short duration still has the edge

If the Fed raises rates in December, as futures markets currently imply, the instruments that reset fastest will benefit first. New 4-week and 13-week bills will price in the higher policy rate, money funds will drift higher over the following weeks as their holdings roll over, and savings accounts will move whenever each bank decides. For investors who believe rates have further to rise, keeping cash in short bills or a government money fund preserves the ability to capture each increase.

This is where many competing guides, written during the 2024 and 2025 easing cycle, give dated advice. Locking in a long CD made sense when the Fed was cutting. With the Fed hiking and core inflation running hot, the case for extending maturity is weaker, at least until there are signs that inflation is rolling over.

When locking in a rate makes sense

Nobody knows how long the hiking cycle will last, so a balanced approach splits near-term savings between a flexible option and a fixed one, such as a 26-week bill or a one-year CD from a well-rated bank.

A simple bill ladder accomplishes the same thing with more precision. Buying equal amounts of 4-, 13-, and 26-week bills, then rolling each one at maturity, creates a steady stream of cash coming due every few weeks. You capture rising rates gradually and always have money maturing soon.

Cash yields and the stock market

Higher cash yields also raise the bar for stocks. When a risk-free bill pays above 4% and the 10-year Treasury yield has been hovering near 5%, investors demand more from equities, and expensive growth stocks feel that pressure most. That dynamic was part of the backdrop to the November sell-off in AI-linked shares. It does not mean cash beats stocks over long horizons, which history does not support, but it does mean the opportunity cost of waiting is lower than it has been for most of the past 15 years.

Investors who want to track how bill yields, fund yields, and their own cash balances shift around each Fed decision can set up recurring checks rather than relying on memory. Alphio's Scheduled Task feature can run a weekly or post-FOMC review on a set schedule so a maturing bill or a stale sweep balance does not slip through the cracks.

Building a Cash Plan That Fits Your Goals

Bucket one: the emergency fund

Start with money you might need on a day's notice. For most households this is three to six months of essential expenses, and it belongs in an FDIC-insured high-yield savings account or a retail government money market fund at your brokerage. The priority here is certainty and speed, not squeezing out the last tenth of a percent. Choose a bank with a consistently competitive rate rather than the highest promotional one, so you are not forced to switch every few months.

Bucket two: known expenses within two years

Money earmarked for a tuition bill, a home down payment, or a tax payment has a known date, which makes it a natural fit for Treasury bills or a bill ladder timed to the expense. The state tax exemption improves the after-tax yield, and matching maturities to spending removes the risk of having to sell at an inconvenient moment. For balances above FDIC limits, bills also avoid the need to spread deposits across multiple banks.

Bucket three: dry powder for investing

Cash you intend to invest in stocks or bonds when prices become attractive should sit where it is instantly available inside your brokerage account, typically in a government money market fund or short Treasury ETF rather than a low-yield sweep. The key is to define in advance what would trigger deployment, such as a specific drawdown in an index, a valuation level, or a rebalancing threshold. Without rules, dry powder tends to stay dry indefinitely.

For investors who want help reasoning through those trade-offs on their own portfolio, Alphio's Conversational Trading lets you ask questions in plain language, compare scenarios, and review positions before acting, while you remain in control of every decision.

Conclusion

The choice between a money market fund, a high-yield savings account, and Treasury bills is less about finding the single highest number and more about matching each dollar to its purpose. As of mid-November 2026, short Treasury bills offer the highest yields and a state tax break, money market funds offer near-instant liquidity inside a brokerage account, and high-yield savings accounts offer FDIC insurance and unmatched simplicity. All three are dramatically better than the 0.38% national average savings rate, and in a Fed hiking cycle, shorter maturities keep you positioned to capture each increase.

The best plan is usually a combination: an insured emergency fund, a bill ladder for known expenses, and a clearly defined pool of investable cash with written rules for when to deploy it. Revisit the mix after each Fed meeting, because the relative appeal of each option shifts as rates move. Tools can help with the discipline. Alphio's Scheduled Task can automate regular reviews of your cash and yields, and Autonomous Trading can execute predefined, rules-based strategies once you have set clear risk limits. Neither replaces your own judgment, and no cash product or tool can guarantee returns, but a deliberate system beats leaving money idle in an account that pays almost nothing.