The five Thrift Savings Plan (TSP) core funds finished the week of September 14–18, 2026 mostly lower, with elevated Treasury yields, oil prices and a hawkish Federal Reserve rate hike contributing to a volatile week that left the G Fund as the only core fund in positive territory.
What Drove the Week
The Federal Open Market Committee (FOMC) raised the federal funds rate by 25 basis points on September 16, a move markets had largely anticipated amid persistent inflation pressures. What drew more attention was the Fed’s outlook and the tone of Fed Chair Kevin Warsh’s post-meeting press conference. Warsh emphasized that inflation remained too high, while the Fed’s updated projections indicated that most policymakers expected at least one additional rate increase before year-end.
The rate decision added to a week that had already been shaped by elevated Treasury yields, oil prices and uneven stock-market performance. Stocks fell following Wednesday’s Fed announcement before paring losses over the back half of the week, but the recovery was not enough to erase the week’s earlier losses across most TSP funds. The I Fund and S Fund ultimately posted the week’s steepest declines, while the C Fund finished nearly flat and the F Fund edged lower. The G Fund posted its customary small, steady gain tied to its government securities rate.
Core Funds
| Fund | Share Price | Weekly Change | YTD Return |
|---|---|---|---|
| G Fund | $20.2236 | +0.09% | +3.25% |
| F Fund | $20.6097 | -0.03% | -1.30% |
| C Fund | $123.4142 | -0.06% | +12.69% |
| S Fund | $113.6009 | -1.06% | +13.14% |
| I Fund | $65.1830 | -1.19% | +17.46% |
Lifecycle Funds
| Fund | Share Price | Weekly Change | YTD Return |
|---|---|---|---|
| L Income | $31.0409 | -0.10% | +6.15% |
| L 2030 | $63.4486 | -0.28% | +9.21% |
| L 2035 | $19.5177 | -0.36% | +10.40% |
| L 2040 | $75.2586 | -0.40% | +11.02% |
| L 2045 | $20.9258 | -0.43% | +11.57% |
| L 2050 | $46.5934 | -0.47% | +12.13% |
| L 2055 | $24.5125 | -0.58% | +14.39% |
| L 2060 | $24.5091 | -0.58% | +14.39% |
| L 2065 | $24.5055 | -0.58% | +14.38% |
| L 2070 | $14.5236 | -0.58% | +14.38% |
| L 2075 | $12.6864 | -0.58% | +14.38% |
The Takeaway
Every Lifecycle Fund lost ground for the week, with the decline growing larger the further out the target date, since the more distant Lifecycle Funds carry heavier allocations to the C, S and I Funds. The week’s market weakness therefore hit the longer-dated Lifecycle Funds harder than those closer to or already in retirement, where the L Income Fund’s heavier G and F Fund weighting cushioned the decline. Year to date, the I Fund remains the top performer among the core funds, and every Lifecycle Fund is still solidly positive for 2026 despite the week’s pullback.