By Brittany R. Ballenstedt bballenstedt@govexec.com May 2, 2008

International investments, the riskiest fund option in the Thrift Savings Plan, led the pack for earnings in April, while only fixed-income bonds lost ground.

The international, or I Fund, which invests in stocks in Europe, Australia and some countries in Asia, grew the most, at 5.55 percent in April. The fund posted 12-month losses of 0.88 percent.

The S Fund, which invests in the stocks of small- and mid-size American companies, was the second-highest earner, growing 5.30 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 common stock, or C Fund. The fund experienced 12-month losses of 5.70 percent.

The C Fund, which tracks the Standard & Poor's 500 Index, grew 4.94 percent last month. Its 12-month losses were 4.61 percent.

The government securities (G) fund, which is the most reliable, earned 0.24 percent last month for a yearlong 4.37 percent increase.

The F Fund was the only one of the five basic options for April to drop, falling 0.16 percent. The fund, made up of fixed-income bonds, still had positive 12-month earnings, at 7.12 percent.

All the TSP's life-cycle fund options, which automatically adjust to more conservative allocations as investors near their target retirement date, saw gains last month. The options designed for younger employees grew the most, because they are the most heavily invested in funds that are riskier but also have greater earnings potential.

The L 2040 fund, designed for TSP participants anticipating retirement around the year 2040, grew 4.26 percent in April. The L 2030 Fund gained 3.74 percent; the L 2020 rose 3.23 percent; the L 2010 increased 1.93 percent; and the L Income, designed for employees with planned retirements in the very near future, gained 1.20 percent.

The L funds with riskier allocations posted losses during 12 months, however. L 2040 lost 1.78 percent, L 2030 lost 0.94 percent, L 2020 gained 0.06 percent, L 2010 earned 2.13 percent and L Income made 3.21 percent.