TSP Fund Returns May 2026: I Fund Leads 2026 at +16.56%

Last Updated: May 31, 2026 Reading Time: 7 min

Every TSP core fund finished May 2026 in the green, and the headline you will see everywhere says the I Fund is leading. That is true for the year, but it misses what actually happened in May. The C Fund won the month at +5.26%. The I Fund's real story is the year-to-date crown: +16.56% through May 31, a lead it has held every single month of 2026.

Key Takeaways

• All five core TSP funds posted gains in May 2026. The C Fund led the month at +5.26%, with the I Fund at +4.90% and the S Fund at +4.49%.
• Year-to-date, the I Fund leads at +16.56%, ahead of the S Fund (+13.48%) and C Fund (+11.26%).
• A $100,000 balance held 100% in the I Fund since January 1 would be worth about $116,560 through May 31.
• The I Fund's 2026 run is a dollar story: a weaker dollar plus strong overseas markets, not anything specific to the TSP or federal employment.
• Chasing the I Fund now is the classic buy-high trap. The drivers behind its lead are cyclical.

May 2026 TSP Returns: Every Fund Finished Positive

So much for "sell in May." All five core funds gained ground. Here is the month alongside the full year so far.

Fund	May 2026	YTD through May
G Fund	+0.39%	+1.80%
F Fund	+0.33%	+0.49%
C Fund	+5.26%	+11.26%
S Fund	+4.49%	+13.48%
I Fund	+4.90%	+16.56%

The C Fund's +5.26% ranked as its 6th-best May in 38 years of history, well above its typical May gain near +1.5%. The G Fund's monthly number looks small because it earns a steady statutory rate that works out to roughly 4.4% on an annual basis, not because it had a weak month. It is doing exactly what it is built to do.

The I Fund Leads 2026, Even Though the C Fund Won May

This is the distinction the one-line headlines skip. "I Fund leads" is a year-to-date statement, not a May statement.

Here is how the lead actually played out, month by month. This is a FedTools compilation of TSP.gov monthly return data that no other site currently publishes in one place.

Month	Monthly winner	Return	YTD leader after	YTD
January	I Fund	+5.94%	I Fund	+5.94%
February	I Fund	+6.05%	I Fund	+12.34%
March	G Fund	+0.34%	I Fund	+1.84%
April	C Fund	+10.49%	I Fund	+11.12%
May	C Fund	+5.26%	I Fund	+16.56%

The I Fund banked such a large cushion in January and February that it has held the annual lead every month since, even though it lost the monthly race in both April and May. March was the only ugly month for everyone: the I Fund fell 9.35% as the dollar briefly strengthened and tariff fears hit international markets, but its early-year head start absorbed the hit.

What $100,000 Would Be Worth in Each Fund

Percentages are abstract. Dollars are not. Here is what a balance invested 100% in a single fund on January 1, 2026 would be worth through May 31, based on the verified year-to-date returns above.

Starting balance	G Fund	F Fund	C Fund	S Fund	I Fund
$50,000	$50,900	$50,245	$55,630	$56,740	$58,280
$100,000	$101,800	$100,490	$111,260	$113,480	$116,560
$200,000	$203,600	$200,980	$222,520	$226,960	$233,120
$500,000	$509,000	$502,450	$556,300	$567,400	$582,800

The gap between the I Fund and the F Fund over five months is more than $16,000 on a $100,000 balance. That spread is the whole argument for why your allocation matters more than any single month's headline.

Why the I Fund Is Winning 2026

Two forces are doing the work, and neither has anything to do with the TSP itself.

A weaker dollar. The I Fund tracks an international index and is not currency-hedged. When the dollar falls, gains earned in euros, yen, and other currencies are worth more after they are converted back to dollars. The U.S. dollar index peaked above 109 in early 2025, broke below 97 in January 2026, touched a near four-year low around 95.5, and sat near 99 in late May. That is still about 10% below its peak, and that decline added several points to I Fund returns in every positive month.

Money rotating out of U.S. stocks. After a decade of U.S. large-cap dominance, global investors shifted money into Europe, Japan, and emerging markets in 2025 and 2026. Cheaper overseas valuations, European stimulus spending, Japanese corporate reform, and uncertainty around U.S. tariff policy all made non-U.S. markets relatively more attractive.

The I Fund's benchmark change also helps. Since 2024 it has tracked a broader index of roughly 5,000 stocks across 44 countries, including emerging markets, instead of the older developed-markets-only benchmark. That broader exposure caught more of the 2026 rally.

The result: the I Fund's trailing 12-month return is about 35.1%, extending a multi-year run that included +32.45% in 2025.

L Fund Returns for May 2026

If you are in a Lifecycle fund, you held a blend of the funds above and did not have to think about any of this. All L Funds gained in May.

L Fund	May 2026	YTD through May
L Income	+1.66%	~4.9%
L 2030	+2.95%	~8.1%
L 2040	+3.71%	~10.0%
L 2050	+4.18%	~11.2%
L 2055 to L 2070	+5.00%	~13.3%

The longer-dated funds hold more stock, so they captured more of the May rally. That is the design working as intended.

Should You Chase the I Fund?

This is the question that gets federal employees in trouble. The honest answer: probably not, and definitely not because of a year-to-date number.

The I Fund's lead came from a falling dollar and a rotation into international stocks. Both are cyclical. The dollar that fell 10% can rebound, and when it does, the same currency math that boosted the I Fund works in reverse. Moving money into a fund after it has already run is how investors lock in high prices right before the cycle turns.

If you are in an L Fund, you do not need to do anything. If you manage your own allocation, the question is whether your current split still fits your time horizon and how much volatility you can stomach, not which fund happened to be hottest over the past five months.

Calculate Your TSP Growth

Want to see where your balance lands at retirement based on your own allocation and contributions, not a single month's returns? Use our free TSP Calculator to project your growth over time. Pair it with the best TSP allocation guide to think through your mix, and the I Fund volatility and rebalancing guide before you react to any hot streak.

Frequently Asked Questions

What did TSP funds return in May 2026?

All five core funds finished positive. The C Fund led the month at +5.26%, followed by the I Fund at +4.90% and the S Fund at +4.49%. The G Fund returned +0.39% and the F Fund +0.33%.

Which TSP fund is leading year-to-date in 2026?

The I Fund leads year-to-date through May 31 at +16.56%, ahead of the S Fund at +13.48%, the C Fund at +11.26%, the G Fund at +1.80%, and the F Fund at +0.49%.

Why is the I Fund leading TSP returns in 2026?

Two drivers: strong international stock markets in Europe, Japan, and emerging markets, and a weaker U.S. dollar. The I Fund is not currency-hedged, so when the dollar falls, overseas gains are worth more once converted back to dollars. The dollar index fell from above 109 in early 2025 to near 95.5 at its early-2026 low.

How much would $100,000 in the I Fund have grown in 2026?

A 100% I Fund position starting at $100,000 on January 1 would be worth about $116,560 through May 31. The same balance in the S Fund would be about $113,480, the C Fund about $111,260, the G Fund about $101,800, and the F Fund about $100,490.

Should I move my TSP into the I Fund after its strong run?

Past performance does not predict future returns. The I Fund's lead has been driven by dollar weakness and global capital rotation, both of which are cyclical. Chasing the hottest fund after a strong run is how investors end up buying high. Pick an allocation that matches your time horizon, then leave it alone.

Related Resources

• TSP Calculator: Project your TSP balance at retirement based on your allocation and contributions.
• April 2026 TSP Returns: The month the C Fund led the biggest single-month rebound of the year.
• March 2026 TSP Returns: The tariff-driven slide when only the G Fund stayed positive.
• Best TSP Allocation 2026: How to think about your fund mix by age and risk tolerance.

Sources: FedSmith: Strong TSP Performance in May 2026, TSP.gov fund performance, TSP.gov I Fund. Year-to-date figures cross-verified against TSPfolio.com as of May 29, 2026. Monthly leadership and dollar-balance tables are FedTools 2026 analysis of TSP.gov monthly return data.