TSP performance in August was positive across the board. After a volatile summer, all five core TSP funds finished the month higher, with the I Fund leading the group.
TSP Performance in August
Here is how the five core funds performed as of August 31, 2026:
| TSP Fund | August | YTD | 12 Months |
| G Fund | 0.41% | 3.00% | 4.46% |
| F Fund | 0.40% | -0.16% | 1.94% |
| C Fund | 2.72% | 13.12% | 20.36% |
| S Fund | 2.27% | 16.10% | 18.68% |
| I Fund | 3.32% | 19.18% | 29.93% |
Returns shown are through August 31, 2026.
The I Fund was the clear leader in August, gaining 3.32%. It was also the strongest performer over both the year-to-date and 12-month periods shown above.
The C Fund gained 2.72% for the month, while the S Fund gained 2.27%. The G and F Funds were much quieter, gaining 0.41% and 0.40%, respectively.
The I Fund Continues to Stand Out
The I Fund’s performance has been one of the more interesting TSP stories of 2026.
International stocks haven’t always been popular with TSP investors, particularly during the long stretch when U.S. stocks significantly outperformed many international markets. This year has looked different.
The I Fund fell 9.35% in March before rebounding 9.11% in April. By the end of August, it had gained 19.18% for the year and 29.93% over the preceding 12 months. That’s a good reminder that strong annual returns don’t necessarily come from a smooth ride.
Some Investors Moved Toward the G Fund
The TSP’s participant activity provides another interesting piece of context. During July, participants moved roughly $1.75 billion into the G Fund, while money flowed out of the C and S Funds. Then the stock funds rebounded in August.
That doesn’t mean moving money into the G Fund was necessarily a mistake. The G Fund has an important role for investors who prioritize stability and preservation of principal.
It does show why market timing is difficult. Moving to safety after a decline can feel like the prudent move, but the recovery may begin before an investor feels comfortable moving back.
What August’s TSP Numbers Mean
For federal employees with decades until retirement, August is just one month in a much longer investment horizon. For someone approaching retirement or already taking withdrawals, however, the relationship between growth, stability, and potential losses becomes more important.
The lesson isn’t that the I Fund was the “right” fund because it won in August. It’s that TSP performance can change quickly, and chasing whichever fund has recently performed best can be just as risky as abandoning investments after a downturn.
Your TSP allocation should ultimately reflect your retirement timeline, income needs, and ability to tolerate market volatility, not simply what performed best last month.
Planning for Retirement?
If you’re approaching retirement, your TSP is only one piece of the puzzle. A Federal Retirement Consultant (FRC®) can help you look at your TSP alongside your FERS pension, Social Security, and other federal benefits to see how the pieces fit together.
