Friday's TSP close

Friday, March 20, was a down day for nearly every TSP fund except the one built to sit still. The G Fund finished at $19.7678, up 0.01%, and is now up 0.9% for the year. It was the only fund in positive territory for the day.

Everything else fell. The C Fund closed at $104.3866, down 1.51%. The S Fund dropped 2.23% to $97.1559, and the I Fund lost 2.33% to $55.4744. The F Fund slipped 0.79% to $20.7592.

Why the funds moved as they did

Each fund follows its benchmark, so the moves line up.

The C Fund tracks the S&P 500, which fell 1.51%. That is the same percentage as the fund, so there is little to explain beyond the index itself. Year to date, the C Fund is down 4.88%.

The S Fund follows the Dow Jones U.S. Completion index, which covers mid-sized and smaller companies outside the S&P 500. Its 2.23% drop was steeper than the large-company loss. Its five-day return is only down 1.27%, which means most of the week's damage came on Friday.

The I Fund follows international stocks excluding China, and it had the worst day at 2.33%. Its five-day loss of 2.27% shows nearly all of that came in this one session.

The F Fund tracks the Bloomberg U.S. Aggregate bond index. Bond prices fall when yields rise, and the 10-year Treasury yield rose to 4.391%, up 2.57% from the prior close. That is roughly 11 basis points. A 0.79% bond decline fits that picture.

The G Fund pays a Treasury-based rate and does not hold prices that swing, so it just kept accruing.

Moves over 1%

Four things stand out. The C, S and I Funds each fell more than 1%, with the I and S Funds both past 2%. The L Funds also fell more than 1% on the day, from 1.12% for L 2030 up to 1.88% for L 2055 and every fund beyond it. L Income lost 0.55%. The F Fund's 0.79% decline was below that mark.

L Funds

L Funds blend the individual funds, so the further the target date, the more stock exposure and the bigger the loss. L 2030 fell 1.12%, L 2040 fell 1.41%, and L 2050 fell 1.60%. L 2055 through L 2075 all fell 1.88%, and all are down 3.39% this year. L Income's 0.35% year-to-date decline is the smallest of the group.

What moved IRA index funds

The IRA benchmarks told the same story. The S&P 500 closed at 6506.48, down 1.51%. The Dow fell 0.96% to 45577.469, and the Nasdaq Composite lost 2.01% to 21647.609, so the heaviest selling hit growth-oriented names.

Among the funds many IRAs hold, VTI (total U.S. stock market) fell 1.57% to $320.34. VXUS (total international stock) lost 3.16% to $74.71. It fell more than the TSP's I Fund because the two cover different sets of countries and companies, and VXUS includes China. BND, the total bond market fund, dropped 0.80% to $73.17, in step with the rise in Treasury yields.

The index data is labeled as the prior session close, but the S&P's move matches the C Fund's exactly. The figures here don't say what triggered the selling, so I won't guess.

What it means for your plan

One day rarely changes a long-term plan, and a drop like this is within the normal range for stock investing. The numbers are a reminder of how the pieces behave. Stocks, both U.S. and international, fell together, bonds slipped as yields rose, and the G Fund did not move. If your account is spread across several of these, your result likely landed somewhere between those extremes.

If you hold a target-date L Fund, it is doing what it was built to do, with bigger swings the further out the date. Nothing in a single Friday close is a reason to rewrite a plan you made with a longer horizon in mind. Check that your mix still matches your timeline and comfort with risk, and let the weekly and yearly numbers carry more weight than any one session.