There aren't ticker symbols for the actual TSP funds because they are not traded like other stock funds. There are however index funds and/or ETFs that the TSP funds track with. See below for the TSP fund equivalents that can generally be found on chart sites or investment trackers.
C Fund: SPX (S&P 500 Index)
S Fund: VXF (Vanguard Extended Market Index Fund ETF)
I Fund: EFA (iShares MSCI EAFE ETF)
F Fund: We use AGG (iShares Core US Aggregate Bond ETF)
G Fund: No market equivalent. This fund is a short-term U.S. Treasury security specially issued to the TSP.
Click the fund name below for a link to the TSP.gov explanation of each fund.