June brought mixed TSP returns for Thrift Savings Plan investors, with a wide performance gap between the funds that track large-cap and small-cap domestic stocks. The S Fund posted its strongest month of the year, while the C Fund gave back some of its recent gains and the I Fund finished essentially flat.
The S Fund’s Moment
The standout story of June was the S Fund’s 4.34% gain — the best single-month TSP returns of any core stock fund in 2026. Small and mid-cap companies benefited from a broadening market rally as investors rotated beyond the largest technology companies into a wider range of sectors. Expectations for lower interest rates and improving economic sentiment also supported smaller companies during the month. The S Fund has now posted three consecutive positive months and leads all core stock funds for the year, up 18.41% through June 30.
The C Fund Takes a Breather
The C Fund declined 0.95% in June, its first negative month since March. The pullback came after back-to-back strong months – the C Fund gained 10.49% in April and 5.26% in May – and should be seen in that context. Despite the June dip, the C Fund remains up 10.20% for the year and 22.31% over the trailing 12 months. After two exceptionally strong months, investors rotated into smaller companies and other sectors, leading many of the largest stocks in the S&P 500 to pause during June.
I Fund Essentially Flat
The I Fund finished June at -0.03%. International markets finished essentially unchanged during June as gains earlier in the month were offset by late-month weakness and currency movements. Despite the flat month, the I Fund remains the strongest performer among core funds on a 12-month basis, up 30.05% over the trailing year and 16.53% year-to-date.
Stability From the Bond Funds
The G Fund and F Fund continued their steady roles in June. The G Fund gained 0.37% with no risk of principal loss, while the F Fund added 0.25% as bond markets absorbed the Federal Reserve’s current steady-rate stance.
June 2026 TSP Returns
| TSP Fund | June Return | YTD Return | 12-Month Return |
|---|---|---|---|
| G Fund | +0.37% | +2.18% | +4.40% |
| F Fund | +0.25% | +0.74% | +3.83% |
| C Fund | -0.95% | +10.20% | +22.31% |
| S Fund | +4.34% | +18.41% | +29.16% |
| I Fund | -0.03% | +16.53% | +30.05% |
| L Income | +0.30% | +5.24% | +10.08% |
A Strong Second Quarter Overall
Despite June’s mixed results, the second quarter as a whole was exceptionally strong for TSP stock fund investors. The C Fund gained 15.20% for the quarter, the S Fund gained 19.88%, and the I Fund gained 14.42% — all driven by April’s broad-based recovery.
Looking Ahead
Markets will continue watching the Federal Reserve for clues about the timing of future interest-rate cuts. Expectations for lower rates have generally been supportive of equities, while any signs that rates may remain higher for longer could increase market volatility. International returns will depend in part on dollar strength and how geopolitical tensions in the Middle East evolve.
Monthly fluctuations like June’s are a normal feature of a diversified TSP portfolio. Investors with long time horizons have significantly more history working in their favor than any single month’s data suggests.
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