After a rough July, three of the funds - C, S and I - experienced modest gains in August. The G Fund saw no change, while the F Fund dropped less than a quarter of a percent in September.
All five funds have increased in value over the past 12 months. The I Fund led the way with a 21.6 percent gain, while the F Fund trailed the pack with a 3.6 percent rise.
Investors in the 401(k)-style federal employee retirement plan can put money into all five funds. With more than 3.2 million federal workers participating, the TSP has more than $135 billion in assets.
The S Fund, which invests in the stock of small and mid-size companies, boasted its highest monthly gain in nearly a year with a 3.9 percent increase in September. In July, the S Fund lost 5.5 percent, and in August the fund posted no gains or losses. The S Fund has gained more than 18 percent over the past 12 months.
The F Fund, which is composed of fixed-income bonds, has gained for four straight months and only significantly declined in April, with a 2.5 percent drop. The fund rose by 3.6 percent in the last 12 months.
The G Fund, which is invested in government securities, remained consistent, gaining 0.4 percent in September for the fifth consecutive month. The fund rose by 4.4 percent over the past 12 months.
The C Fund, which consists of common stocks, gained for the second month in a row, with an increase of 1.1 percent in August. The fund dropped 3.2 percent in July, but has increased by 13.9 percent over the past year.
The I Fund, which invests in international stocks, continued its growth spurt with a 2 percent increase. The fund underwent the largest 12-month gain, with a 21.6 percent increase.