The Five Individual TSP Funds
The Thrift Savings Plan offers five individual investment funds, each with a distinct investment objective and risk profile. Understanding how each fund works is the foundation of building a TSP allocation strategy that matches your goals, timeline, and risk tolerance. Too many federal employees default to the G Fund or a Lifecycle fund without understanding the trade-offs they are making.
Let's break down each fund so you can make informed decisions about where your money goes.
The G Fund: Government Securities Investment Fund
The G Fund is the safest option in the TSP. It invests exclusively in a special non-marketable U.S. Treasury security that is guaranteed by the full faith and credit of the United States government. Your principal is protected — the G Fund has never had a negative return in any month since the TSP's inception in 1987.
The G Fund earns interest based on the weighted average yield of all outstanding Treasury notes and bonds with four or more years to maturity. In practice, this means you get a return similar to long-term Treasury bonds but without the price volatility that bond investors normally experience. It is a unique investment available only through the TSP.
Historical average annual return: Approximately 3.5% to 4.5% over the past two decades, though recent years have seen both lower and higher returns depending on the interest rate environment.
Best for: Money you cannot afford to lose, short-term needs, and as a stabilizer within a diversified portfolio. Retirees who need to draw from their TSP within one to three years often keep that portion in the G Fund.
Limitations: The G Fund's returns may not keep pace with inflation over long periods. If you are 20 or 30 years from retirement, relying heavily on the G Fund means your purchasing power may erode over time.
The F Fund: Fixed Income Index Investment Fund
The F Fund tracks the Bloomberg U.S. Aggregate Bond Index, which includes a broad mix of investment-grade U.S. bonds — government bonds, mortgage-backed securities, and corporate bonds. Unlike the G Fund, the F Fund invests in marketable bonds, which means its value fluctuates with interest rates.
When interest rates rise, bond prices fall, and the F Fund can have negative returns. When rates fall, bond prices rise and the F Fund benefits. This inverse relationship with interest rates is the primary risk factor for the F Fund.
Historical average annual return: Approximately 4% to 5% over the long term, though it experienced negative returns in 2013 and notably in 2022 when interest rates rose sharply.
Best for: Investors seeking higher returns than the G Fund with moderate risk, and as a diversifier alongside stock funds. Bonds often move differently from stocks, so holding some F Fund can reduce portfolio volatility.
Limitations: Not risk-free. Rising interest rates can cause meaningful losses. The F Fund is less predictable than the G Fund but has historically offered modestly higher returns.
The C Fund: Common Stock Index Investment Fund
The C Fund tracks the S&P 500 Index, which represents the 500 largest publicly traded U.S. companies. This is the core large-cap stock fund of the TSP and the most widely held equity option among federal employees. Companies in the S&P 500 include household names across every sector of the economy.
The C Fund has historically been the strongest long-term performer among the TSP stock funds, though it is also subject to significant short-term volatility. In strong bull markets, the C Fund can return 20% or more in a single year. In bear markets, it can lose 30% or more.
Historical average annual return: Approximately 10% to 11% annually since inception, though individual years vary dramatically.
Best for: Long-term growth. If you are more than 10 years from retirement, the C Fund should likely be a significant portion of your allocation. It offers exposure to the largest, most established U.S. companies.
Limitations: Concentrated in large-cap U.S. stocks only. Does not include small- and mid-cap companies or international stocks. Subject to market downturns that can be severe and prolonged.
The S Fund: Small Cap Stock Index Investment Fund
The S Fund tracks the Dow Jones U.S. Completion Total Stock Market Index, which includes all U.S. stocks that are not in the S&P 500. This means the S Fund covers small-cap and mid-cap companies — thousands of smaller, often faster-growing firms that complement the large-cap C Fund.
When combined with the C Fund, the S Fund gives you exposure to essentially the entire U.S. stock market. Historically, small-cap stocks have outperformed large caps over very long periods, though with higher volatility and longer stretches of underperformance.
Historical average annual return: Approximately 9% to 11% over the long term, with wider swings than the C Fund in any given year.
Best for: Investors seeking growth who want broader U.S. stock exposure beyond the S&P 500. The S Fund complements the C Fund well, and many financial professionals recommend holding both in proportion to the overall market (roughly 80% C and 20% S to approximate the total U.S. stock market).
Limitations: More volatile than the C Fund. Small-cap stocks can underperform for extended periods, and individual years can see dramatic losses. Not suitable as a standalone allocation for risk-averse investors.
The I Fund: International Stock Index Investment Fund
The I Fund tracks the MSCI Europe, Australasia, Far East (EAFE) Index, which includes large- and mid-cap stocks from developed international markets. This gives you exposure to major companies in Europe, Japan, Australia, and other developed economies outside the United States.
International diversification is important because U.S. and international stock markets do not always move in tandem. There have been extended periods — sometimes lasting a decade or more — where international stocks outperformed U.S. stocks, and vice versa. Holding some international exposure hedges against the risk that the U.S. market alone underperforms.
Historical average annual return: Approximately 6% to 8% annually since inception, though returns have lagged U.S. stocks during the past decade of U.S. market dominance.
Best for: Diversification. Adding the I Fund to a portfolio of C and S Funds reduces concentration risk in the U.S. market and provides exposure to global economic growth.
Limitations: Does not include emerging markets (China, India, Brazil, etc.), so it misses some of the fastest-growing economies. Currency fluctuations between the U.S. dollar and foreign currencies affect returns. A strong dollar reduces I Fund returns; a weak dollar boosts them.
Building Your TSP Allocation Strategy
There is no single correct allocation for everyone. Your ideal mix depends on your age, retirement timeline, risk tolerance, and other income sources. Here are some general frameworks:
- 20+ years to retirement: Consider a growth-oriented allocation such as 60% C Fund, 15% S Fund, 15% I Fund, and 10% F or G Fund. You have time to ride out market downturns.
- 10 to 20 years to retirement: A balanced allocation such as 45% C Fund, 10% S Fund, 10% I Fund, 15% F Fund, and 20% G Fund provides growth with increasing stability.
- Within 5 years of retirement: Shift toward more conservative holdings. Consider 30% C Fund, 5% S Fund, 5% I Fund, 20% F Fund, and 40% G Fund. Protecting your balance becomes more important as you approach withdrawal.
- In retirement: Your allocation should reflect your withdrawal needs. Keep one to three years of expected withdrawals in the G Fund, with the remainder allocated to growth funds to maintain purchasing power over a multi-decade retirement.
Lifecycle Funds: The Hands-Off Alternative
If selecting your own allocation feels overwhelming, the TSP's Lifecycle (L) Funds do it for you. Each L Fund targets a specific retirement year and automatically adjusts its allocation from aggressive (heavy in C, S, and I Funds) to conservative (heavy in G and F Funds) as the target date approaches.
L Funds are a perfectly reasonable option for employees who want a set-it-and-forget-it approach. However, they may not be optimal for your specific situation, especially if you have other retirement accounts or income sources that should be considered in your overall allocation.
Rebalancing and Staying the Course
Whatever allocation you choose, rebalance periodically — quarterly or annually — to maintain your target percentages. Market movements will cause your allocation to drift. For example, a strong year for stocks could push your equity allocation above your target, increasing your risk exposure without your realizing it.
The TSP makes rebalancing easy through interfund transfers, which you can execute online at tsp.gov. You can also set your contribution allocation to direct new contributions toward underweight funds, which gradually rebalances your portfolio over time.
Most importantly, avoid making emotional changes to your allocation during market volatility. History shows that investors who sell during downturns and wait for recovery to reinvest consistently underperform those who stay the course. Your allocation should reflect your long-term plan, not today's headlines.