Eight of the 10 funds in the Thrift Savings Plan suffered losses in January after several months of growth.

The I Fund, which invests in overseas companies, posted the biggest losses for the month, falling 5.17 percent in January. During the past 12 months, though, its value was up 40.01 percent, the second-highest gain for that period among TSP funds.

The C Fund, invested in common stocks of large companies on the Standard & Poor's 500 Index, suffered the second-largest decline in January, falling by 3.60 percent, though it has grown 33.33 percent during the past year. Among the non-life-cycle funds, the S Fund, which invests in small and mid-size companies and tracks the Dow Jones Wilshire 4500 Index, had the third-largest losses, falling 2.43 percent, though it has the largest growth of any fund, rising 43.31 percent.

Both the G Fund, government securities, and the F Fund, which invests in fixed-income bonds, both posted modest gains in January. The G Fund rose 0.29 percent and was up 3.08 percent for the past 12 months, while the F Fund climbed 1.54 percent and was up 8.56 percent.

All the life-cycle funds, which switch from a riskier to a more stable mix of investments as participants near retirement, fell in January. The L 2040 Fund was down 2.88 percent, the L 2030 Fund declined 2.49 percent, the L 2020 Fund fell 2.03 percent, the L 2010 Fund lost 0.58 percent of its value, and the L Income Fund was down 0.45 percent.

But all those funds still climbed during the past 12 months. The L 2040 Fund has gained 31.86 percent, the L 2030 Fund rose 27.99 percent, the L 2020 Fund grew 23.63 percent, the L 2010 Fund is up 12.33 percent, and the L Income Fund has gained 10 percent.