The G Fund: The Only Investment That Never Has a Bad Day
By William Carrington, CFP®, RMA®
In a recent post, I wrote about custodians — the institutions that make sure your money can't be stolen. Today I want to look at the other reassurance people want: is there anywhere my money can't lose value? For the millions of federal employees and uniformed services members with a Thrift Savings Plan account, the answer has a name, and it's probably the most remarkable investment vehicle most of its owners have never fully understood: the G Fund.
What makes the G Fund different from everything else
Formally the Government Securities Investment Fund, the G Fund invests in U.S. Treasury securities specially issued to the TSP — they don't trade on any market, and you can't buy them anywhere else. Payment of both principal and interest is guaranteed by the U.S. government. The practical result is something no other fund in the TSP, and essentially no fund anywhere, can say: the G Fund's value never goes down. Not during the 2008 crisis, not during the 2020 crash, not during the 2022 bond rout. Interest is credited daily, and you will never open your account to find your G Fund balance lower than it was yesterday.
That last example — 2022 — deserves a closer look, because it dispels the most common misconception. People assume "safe" and "bonds" are the same thing. In 2022, the F Fund — the TSP's broad bond index fund — lost roughly 13% as rising interest rates hammered bond prices. Bonds are safer than stocks; they are not safe from loss. The G Fund was the fund that posted positive returns that year, because its structure is fundamentally different: its securities don't get repriced by the market each day, so there's simply no mechanism for the value to fall. The U.S. government absorbs the interest-rate risk so you don't have to.
The built-in sweetener: the yield advantage
Here's the genuinely clever part of the design. Normally, investments that can't lose value pay stingy short-term rates — think money market funds and savings accounts. The G Fund's interest rate, though, is recalculated monthly based on the average yield of Treasury securities with four or more years to maturity. In other words, you earn a long-term rate on what is effectively an overnight security. As of July 2026, that rate is 4.5%. This "yield advantage" is why the G Fund typically outpaces money market funds and Treasury bills over time — and it's a deal available exclusively inside the TSP. It also costs almost nothing to own: there's no investment management fee, just the TSP's administrative expense of roughly three or four cents per $100 per year.
The fine print: two things worth knowing
Inflation is the real risk. The G Fund cannot lose dollars, but it can lose purchasing power. Its guarantee is nominal, not inflation-adjusted, and there have been stretches — the 2023–2024 inflation spike among them — where prices rose faster than the G Fund earned. An account that never has a down day can still fall behind the cost of living. This is the trade you're making, and it's why "never loses value" and "always a good idea" are not the same sentence.
Debt-ceiling headlines are noise, not danger. Every few years, a debt-limit standoff produces alarming stories about the Treasury "tapping" or "suspending" the G Fund as part of its extraordinary measures. Here's what those stories rarely explain: by law, the fund must be made completely whole afterward — principal and every penny of interest restored as if nothing happened. No participant has ever permanently lost a cent of principal or interest to a debt-ceiling impasse. Your balance catches up automatically. This is a headline designed to raise your blood pressure, not a threat to your retirement.
How to think about the G Fund's job
The G Fund is the most popular single fund in the TSP, and its safety is precisely why that popularity cuts both ways. Used well, it's the stability anchor of a portfolio: the portion of your money whose job is to be there — to cover near-term needs in retirement, to keep you from selling stocks in a downturn, to let the growth assets do their volatile work without forcing you to touch them at the wrong moment.
Used poorly, it becomes what some advisors call the G Fund trap: fleeing to it during a market drop — which locks in losses and misses the recovery — or parking an entire career's worth of contributions there, where decades of inflation do what no market crash ever could. Safety from loss is not the same as safety from falling short. A thirty-year retirement funded entirely at G Fund rates is, for most households, a plan to run out of purchasing power.
The right amount of G Fund is a personal answer — it depends on your pension, your time horizon, your withdrawal needs, and honestly, your temperament. But the framework is simple: the G Fund's job is stability, not growth. Size it to the part of your life that needs certainty, and let the rest of your portfolio do the growing.
The bottom line
Between an independent custodian guarding your accounts from theft and an instrument like the G Fund guarding a portion of your savings from loss, there is more genuine safety built into the system than most people realize — each piece doing a specific job, none doing every job. Your money can be protected from theft entirely. It can be protected from nominal loss entirely. What nothing can fully protect it from is inflation — and managing that risk is what the rest of thoughtful investing is for.
William Carrington, CFP®, RMA®, is a fee-only fiduciary financial planner and principal of Carrington Financial Planning LLC.