Throwback Thursday Classic Post – Thrift Savings Plan Fund Deep Dive – The S Fund

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There are only five investments available in the Thrift Savings Plan (TSP), so let’s take a detailed look at them one at a time. In this post we’ll cover the S Fund. You can combine the S Fund with the C Fund to invest in the entire US stock market.

Inception Date

1 MAY 2001

Fund Management

The Federal Retirement Thrift Investment Board currently contracts BlackRock Institutional Trust Company, N.A. (BlackRock) to manage the S Fund assets. The S Fund remains invested regardless of the performance of the securities markets or the overall economy.

Investment Strategy

The S Fund is invested in a stock index fund that invests in small to medium-sized U.S. companies that are not included in the C Fund. The S Fund’s objective is to match the performance of the Dow Jones U.S. Completion TSM Index, which means that when you combine the S Fund and C Fund you are investing in the entire US stock market. Also, some of the money in the S Fund is temporarily invested in the G Fund and earns the G Fund return.

The S Fund is a passively managed fund that remains invested according to its indexed investment strategy regardless of stock market movements or general economic conditions.

What is the Risk?

Your investment in the S Fund is subject to market risk because the prices of the stocks it invests in rise and fall. You are also exposed to inflation risk, meaning your S Fund investment may not grow enough to offset inflation.

What is the Benefit?

Historically, this increased risk has been rewarded with an increased return. It offers the opportunity to experience gains from equity ownership of small and medium-sized US company stocks. Here is all the performance data as of 24 OCT 2020:

Screen Shot 2020-10-24 at 12.28.00 PM

Types of Earnings

The S Fund changes in value as the market price of its stocks change. In addition, the S Fund makes money for its investors when those stocks pay dividends. Unlike a traditional mutual fund, though, income from dividends is included in the share price calculation. It is not paid directly to participants’ accounts.

It also makes some money on interest on short-term investments and securities lending income.

BlackRock credits interest and dividend income each business day. This income is then reflected in the TSP share prices.

Share Price Calculations

The value of your account is determined each business day based on the daily share price and the number of shares you hold. At the end of each business day, after the stock and bond markets have closed, the total value of the funds’ holdings (net of accrued administrative expenses) is divided by the total number of shares outstanding to determine the share price for that day. The daily change in TSP share prices reflects all investment income (interest on short-term investments, dividends, capital gains or losses, and securities lending income) net of TSP administrative expenses.


The net expenses paid by investors is 0.042% or 4.2 basis points, which like all the TSP funds is ridiculously low and is a major benefit of the TSP. It cost $0.42 for each $1,000 invested.

How Should I Use the S Fund in my TSP Account?

The S Fund can be useful in a portfolio that also contains stock funds that track other indexes such as the C Fund (which tracks an index of large U.S. company stocks) and the I Fund (which tracks an index of international stocks). The C, S, and I Funds track different segments of the overall stock market without overlapping. This is important because the prices of stocks in each market segment don’t always move in the same direction or by the same amount at the same time. By investing in all segments of the stock market (as opposed to just one), you reduce your exposure to market risk.

The S Fund can also be useful in a portfolio that contains bonds. Again, it is because the prices of stocks and bonds don’t always move in the same direction or by the same amount at the same time. So a retirement portfolio that contains a bond fund like the F Fund, along with other stock funds, like the C and I Funds, will tend to be less volatile than one that contains stock funds alone.

Advice from My Favorite Short Investing Book

Here is what my favorite investing book, The Elements of Investing: Easy Lessons for Every Investor, says about small and mid-cap funds like the S Fund:

The S&P 500 [C Fund in the TSP] represents only about 70 percent of the total value of all stocks traded in the United States. It excludes the 30 percent made up of smaller companies [which are in the S Fund], many of which are the most entrepreneurial and capable of the fastest future growth.

If you want to invest in the entire US stock market, you just combine the C Fund with the S Fund in a 3:1 ratio. To see how I use the S Fund, read the Crush the TSP series.

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