The I Fund, which invests in international stocks, grew the most, at 2.57 percent. March's growth brings the fund's 12-month gains to 20.22 percent -- also the highest increase of any fund over that period.
The C Fund, which tracks the Standard & Poor's 500 Index, gained 1.09 percent for March, bringing the 12-month increase to 11.83 percent.
The S Fund, which invests in the stocks of small- and mid-sized American companies, also grew 1.09 percent last month. The fund tracks the Dow Jones Wilshire 4500 Index, which invests in the 4,500 next largest domestic companies after the 500 tracked by the C Fund. The S Fund's 12-month gains stand at 9.30 percent. The government securities, or G Fund, which is the most reliable TSP fund, earned 0.42 percent last month for a yearlong 5.05 percent increase.
The fixed-income bonds included in the F Fund made no movement in March, placing them at the bottom of the pack for the month. But the fund came in with 6.6 percent gains for the year, placing it ahead of the G Fund.
All of the TSP's life cycle fund options, which automatically adjust as investors near their target retirement date, grew this month. Those designed for younger employees posted the greatest gains, because they invested more heavily in the I, C and S funds.
The L 2040 fund, designed for TSP participants anticipating retirement around the year 2040, grew 1.34 percent. The L 2030 Fund gained 1.16 percent; the L 2020 rose 1.08 percent; the L 2010 increased 0.89 percent; and the L Income, designed for employees with planned retirements in the very near future, gained 0.62 percent.
March's performance marked a reversal from February, when a steep drop in the Dow Jones industrial average caused slight losses among the funds that have grown the most over the past year.