TSP S Fund vs I Fund
The S Fund tracks the Dow Jones U.S. Completion Total Stock Market Index: U.S. small and mid-size companies not in the S&P 500. The I Fund tracks the MSCI ACWI IMI ex USA ex China ex Hong Kong Index: international stocks in developed and emerging markets. From 2004 through 2025, the S Fund averaged 9.94% a year and the I Fund 6.86%, and the S Fund came out ahead in 13 of 22 years.
Side by side
| S Fund | I Fund | |
|---|---|---|
| Compound average (2004–2025) | 9.94% | 6.86% |
| Best year | +38.35% (2013) | +32.45% (2025) |
| Worst year | -38.32% (2008) | -42.43% (2008) |
| Years with a loss | 5 of 22 | 6 of 22 |
| 2026 so far | +12.32% | +13.45% |
S Fund
The S Fund holds U.S. stocks that are not in the S&P 500, mostly small and mid-size companies. Together, the C and S Funds cover nearly the whole U.S. stock market. As of December 31, 2025, the latest date tsp.gov shows, its largest sectors were industrials (19.1%), information technology (18.3%), financials (16.3%) and health care (14.2%), and its largest holdings included Snowflake, Marvell Technology, Cloudflare and Vertiv. It holds most of the index's companies worth more than $1 billion and uses sampling for the smaller ones. Its total expense ratio was 0.051%, or $0.51 per $1,000 invested.
Risk: Stock fund: typically more volatile than the C Fund, with larger daily swings in both directions.
S Fund detailsI Fund
The I Fund holds stocks of companies outside the United States, in both developed and emerging markets, excluding China and Hong Kong. As of December 31, 2025, the latest date tsp.gov shows, its index held more than 5,000 stocks in 44 countries; the largest were Japan (16.14%), the United Kingdom (9.83%) and Canada (9.15%). Its index changed in 2024 to add emerging markets.
Risk: Stock fund: exposed to foreign markets and currency changes, which add ups and downs.
I Fund detailsReturns by year
| Year | S Fund | I Fund | Difference |
|---|---|---|---|
| 2025 | +11.38% | +32.45% | -21.07% |
| 2024 | +16.93% | +4.27% | +12.67% |
| 2023 | +25.30% | +18.38% | +6.91% |
| 2022 | -26.26% | -13.94% | -12.32% |
| 2021 | +12.45% | +11.45% | +1.00% |
| 2020 | +31.85% | +8.17% | +23.68% |
| 2019 | +27.97% | +22.47% | +5.49% |
| 2018 | -9.26% | -13.43% | +4.16% |
| 2017 | +18.22% | +25.42% | -7.20% |
| 2016 | +16.35% | +2.10% | +14.25% |
| 2015 | -2.92% | -0.51% | -2.41% |
| 2014 | +7.80% | -5.27% | +13.06% |
| 2013 | +38.35% | +22.13% | +16.22% |
| 2012 | +18.57% | +18.62% | -0.05% |
| 2011 | -3.38% | -11.81% | +8.43% |
| 2010 | +29.06% | +7.94% | +21.12% |
| 2009 | +34.85% | +30.04% | +4.81% |
| 2008 | -38.32% | -42.43% | +4.11% |
| 2007 | +5.49% | +11.43% | -5.94% |
| 2006 | +15.30% | +26.32% | -11.02% |
| 2005 | +10.45% | +13.63% | -3.18% |
| 2004 | +18.03% | +20.00% | -1.97% |
Common questions
What's the difference between the TSP S Fund and I Fund?
The S Fund tracks the Dow Jones U.S. Completion Total Stock Market Index: U.S. small and mid-size companies not in the S&P 500. The I Fund tracks the MSCI ACWI IMI ex USA ex China ex Hong Kong Index: international stocks in developed and emerging markets.
Which has returned more, the S Fund or the I Fund?
From 2004 through 2025, the S Fund's compound average was 9.94% a year and the I Fund's 6.86%. The S Fund came out ahead in 13 of 22 calendar years. Past performance does not predict future returns.
See every fund's returns by year, or get the free morning briefing on what moved each fund.
Source: official TSP share prices (tsp.gov), through Monday, November 9, 2026. Past performance does not guarantee future results. Educational information, not investment advice; which funds to use is your decision.
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