Ever feel like the stock market is just a handful of tech giants and nothing else? You look at the S&P 500, and it’s basically just the same five or six names sucking up all the oxygen in the room. If you’re a federal employee with a Thrift Savings Plan (TSP) or just someone trying to diversify, you've likely bumped into a weird acronym: DJ US Completion TSM.
Honestly, it sounds like technical jargon designed to make your eyes glaze over. But here's the thing—it’s actually the "secret sauce" for a lot of successful long-term investors.
Basically, the DJ US Completion TSM (the Dow Jones U.S. Completion Total Stock Market Index) is the part of the market that the S&P 500 leaves behind. It’s the "everything else" index. While the S&P 500 tracks the 500 largest U.S. companies, this index tracks literally every other U.S. company that has a readily available stock price. We’re talking thousands of small-cap and mid-cap companies.
What Really Happened With DJ US Completion TSM in 2025 and Beyond?
The last year has been a wild ride for the mid and small-cap sectors. For a long time, the mega-caps—your Apples, your Nvidias, your Microsofts—were the only things moving the needle. But as we’ve seen throughout 2025 and moving into early 2026, the market breadth is finally starting to widen.
According to recent data from January 16, 2026, the index (often tracked via the ticker DWCPF) closed around 2,634.19. It hasn't been a straight line up. Just a couple of days ago, the index was sitting at 2,610.4. It’s volatile. That’s the nature of the beast when you’re dealing with smaller companies that are more sensitive to interest rates and domestic economic shifts.
Why does this matter?
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Because when the "Big 500" get too expensive, investors start hunting for value elsewhere. That "elsewhere" is exactly what the DJ US Completion TSM represents.
The TSP Connection: The S Fund
If you have a TSP, you know this index as the S Fund.
It's the aggressive sibling to the C Fund. While the C Fund mirrors the S&P 500, the S Fund is tethered to the DJ US Completion TSM. In late 2025, there was plenty of chatter on investor forums about the index taking out its December 2024 highs, proving that the mid-cap "engine" of the U.S. economy was finally humming again.
Some people call it garbage when it’s down, but when it rallies, it usually leaves the large caps in the dust.
DJ US Completion TSM: What Most People Get Wrong
The biggest misconception is that this is just a "small cap" index. It’s not.
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It’s an extended market index. This means it includes mid-cap companies that are often huge—billions of dollars in market cap—but just haven't made the cut for the S&P 500 yet. Think of it as the waiting room for greatness. When a company like Uber or Airbnb finally moves into the S&P 500, they actually leave the DJ US Completion TSM.
- Market Cap Coverage: It covers roughly the "bottom" 15-20% of the market by capitalization.
- The Number of Stocks: While the S&P 500 is... well, 500 stocks, this index holds thousands.
- Sector Diversification: You get a much heavier dose of Industrials, Financials, and Real Estate here than you do in the tech-heavy S&P 500.
Real Performance Data (As of January 2026)
Let's look at the hard numbers. Over the last 12 months, the Dow Jones U.S. Completion TSM has seen a change of roughly 12.0%.
For comparison, back in the third quarter of 2025, the index advanced 8.87%, outperforming many mid-cap blend funds. In August 2025, it jumped 4.05% on the back of news that the U.S. economy grew at a 3.3% clip. It’s very much a "pro-growth" index. If the U.S. consumer is spending and small businesses are hiring, this index is where you see the results first.
However, the risk is real.
Investments in smaller companies involve higher volatility. We saw the index range from a 52-week low of about 1,748 to current levels over 2,600. That’s a massive swing. If you can’t stomach a 20% drop in a bad month, this might not be the place for your entire life savings.
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Why TSM (Taiwan Semiconductor) Keeps Popping Up in These Searches
You might see "TSM" and think of the index, but it's important to clear up a common search confusion. Taiwan Semiconductor Manufacturing Company (TSM) is a massive individual stock.
In early 2026, TSM shares jumped over 4% after blowout earnings and an announcement that they plan to spend upwards of $56 billion on capital expenditures in the United States. While TSM is a global titan, it is not a component of the DJ US Completion TSM index because it’s a foreign-based mega-cap.
The "TSM" in the index name stands for Total Stock Market, referring to the broader universe of U.S. equities. Don't let the ticker symbols trip you up. One is a chip maker; the other is a benchmark for thousands of American businesses.
Actionable Insights for Your Portfolio
If you're looking to put this information to work, here is how the pros usually handle the DJ US Completion TSM:
- Check Your Overlap: If you own a "Total Stock Market" fund (like VTI or ITOT), you already own this index. You don't need to buy it twice.
- The 80/20 Rule: Many institutional advisors, including those overseeing the Federal Retirement Thrift Investment Board, suggest that combining the S&P 500 with the DJ US Completion TSM provides 100% coverage of the investable U.S. market. A common split is 80% Large Cap (C Fund) and 20% Completion Index (S Fund).
- Watch the Divisor: The index is reconstituted annually in June. This is when the "winners" get moved up to the big leagues and new startups are added. Keep an eye on the June rebalancing if you track individual mid-cap stocks.
- Tax Considerations: If you’re holding a fund like the Fidelity Extended Market Index Fund (FSMAX), which tracks this index, remember that smaller companies can sometimes trigger more capital gains distributions than steady large-cap stocks.
The DJ US Completion TSM is the pulse of the American entrepreneurial spirit. It’s where the next giants are currently growing. Whether you access it through the TSP S Fund or an ETF like VXF, it remains the most effective way to ensure you aren't just betting on a few tech billionaires, but on the entirety of the U.S. economy.
Stop looking at the Dow 30 or the S&P 500 as the "whole market." They aren't. To see the full picture, you have to look at the completion.