After a tumultuous December in which most funds in the federal government’s 401(k)-style retirement savings program ended in the red, all portfolios in the Thrift Savings Plan rebounded in the first month of 2019.

The S Fund, which is made up of small- and mid-size businesses, led the way, growing 11.64 percent in January. And the common stocks of the C Fund increased by 8.01 percent last month.

The international investments of the I Fund increased 6.60 percent, while the fixed income (F) Fund grew 1.07 percent. The G Fund, which is made up of government securities, increased by its statutorily mandated 0.23 percent.

The TSP’s lifecycle funds, which shifts investments to more stable portfolios as participants get closer to retirement, all saw gains in January. The L Income Fund, for people who have already begun withdrawing money, increased 1.83 percent. The L 2020 grew, 2.53 percent; L 2030, 4.92 percent; L 2040, 5.86 percent; and L 2050, 6.67 percent.