You’ve probably heard that the S&P 500 is "the market." It’s the big one. The one everyone tracks on the evening news. But honestly, if you only look at the S&P 500, you’re missing a massive chunk of the American economy. You're basically ignoring thousands of companies that are doing the legwork behind the scenes.
This is where the Dow Jones U.S. Completion Total Stock Market Index comes in.
It’s a mouthful of a name, I know. Most people just call it the "Completion Index" or use its ticker, DWCPF. Think of it as the "everything else" index. If the S&P 500 is the varsity team, the Dow Jones U.S. Completion Total Stock Market Index is the rest of the school—the up-and-comers, the mid-sized workhorses, and the small-town heroes that haven't hit the big leagues yet.
Why the Dow Jones U.S. Completion Total Stock Market Index Actually Matters
Most investors think they are diversified because they own an S&P 500 fund. They aren't. Not really. When you buy the S&P 500, you are buying the 500 largest companies in the U.S. That's about 80% of the market value. But what about the other 20%?
The Dow Jones U.S. Completion Total Stock Market Index captures exactly what’s left over.
It’s designed to be the perfect puzzle piece. If you take the S&P 500 and snap it together with this index, you get the Dow Jones U.S. Total Stock Market Index. You get everything. No gaps. No missed opportunities.
Right now, as we move through January 2026, this index is sitting with about 3,375 constituents. That is a lot of companies. We are talking about names like Snowflake (SNOW), Marvell Technology (MRVL), and Cloudflare (NET). These aren't tiny "mom and pop" shops. Some have market caps in the tens of billions. They just haven't been invited to the S&P 500 club yet—often because of strict profitability requirements or simply because there’s no room at the top.
The "Hidden" Growth Engine
Smaller companies tend to move differently than the giants. When Nvidia or Apple farts, the S&P 500 catches a cold. But the Completion Index doesn't always follow that script.
Historically, this index thrives during bull markets when investors are feeling "risk-on." Small and mid-cap stocks often have more room to run. It's easier for a $2 billion company to double its value than it is for a $3 trillion company.
But it’s a double-edged sword.
You’ve got to be able to stomach the swings. As of mid-January 2026, the one-year return for the Dow Jones U.S. Completion Total Stock Market Index was roughly 12.69%. Not bad, right? But it’s been a bumpy ride compared to the relative "safety" of the blue chips. During the flat start to 2026, where the Dow Jones Industrial Average has been wobbling due to Fed uncertainty and talk of credit card interest rate caps, these mid-tier companies have shown they can be quite sensitive to the macro environment.
Breaking Down the Components
If you looked under the hood of the Dow Jones U.S. Completion Total Stock Market Index today, you'd see a heavy tilt toward Technology and Industrials.
Technology makes up a huge portion—we're talking about companies like MicroStrategy (MSTR) and Vertiv Holdings (VRT). These are the firms building the infrastructure for the AI boom that everyone is obsessed with. While the "Magnificent Seven" get the headlines, the companies in the Completion Index are often the ones supplying the parts or the software that makes the whole thing work.
- Technology: Around 38% (if you look at the total market context)
- Financials: Deeply represented through regional banks
- Health Care: Biotechs like Alnylam Pharmaceuticals (ALNY)
- Consumer Services: Names like Flutter Entertainment (FLUT)
It's a wild mix.
One day you're tracking a cloud computing firm, the next you're looking at a company that makes specialized valves for oil rigs. That’s the beauty of it. You aren't bettting on a single sector; you're betting on the broad middle of the American economy.
Is It Better Than the S&P 500?
Kinda. Sorta. It depends.
(I know, you hate that answer.)
But look at the data. Over the last decade, the S&P 500 has actually outperformed the broader market in many years. This is weird because "theory" says small caps should pay you a premium for the extra risk. But the 2010s and early 2020s were the era of the Mega-Cap. The giants just kept getting bigger.
However, many analysts, including those over at S&P Global, point out that cycles eventually turn. If you believe that the "Magnificent Seven" are overvalued and that the next decade of growth will come from the "next" big things, then the Dow Jones U.S. Completion Total Stock Market Index is where you want to be.
The "Earnings Filter" Secret
Here is something most people don't realize: To get into the S&P 500, a company generally has to be profitable for four consecutive quarters.
The Dow Jones U.S. Completion Total Stock Market Index doesn't care as much about that.
It’s more inclusive. It includes the "disruptors" that are spending every penny they make on growth. This means you get access to companies earlier in their lifecycle. If you waited for some of these companies to become profitable enough for the S&P 500, you might miss the first 500% of their stock price gain.
Of course, the downside is that you also own the "zombies"—the companies that aren't making money and maybe never will. That’s why the index has over 3,000 stocks; it’s a "spray and pray" approach to innovation.
How to Actually Invest in It
You can't buy "an index" directly. You have to buy a fund that tracks it.
The most famous one is the Vanguard Extended Market ETF (VXF). It’s basically a carbon copy of the Dow Jones U.S. Completion Total Stock Market Index. If you already own an S&P 500 fund (like VOO or SPY), adding VXF effectively turns your portfolio into a "Total Stock Market" portfolio.
Fidelity also has the Fidelity Extended Market Index Fund (FSMAX).
The fees on these are usually dirt cheap. We're talking 0.05% or lower. At that price, you're getting exposure to thousands of companies for the cost of a cup of coffee per year on a $10,000 investment.
Actionable Insights for Your Portfolio
If you're looking at your brokerage account and wondering what to do with this info, here is the play:
Check your overlap. If you own a "Total Stock Market" fund (like VTSAX or VTI), you already own this index. You don't need to do anything. You’re covered.
Identify the gap. If you only own the S&P 500 or the Dow 30, you are 100% missing out on the mid-cap and small-cap growth happening right now. You might consider carving out 10-20% of your U.S. equity sleeve for an "Extended Market" fund to capture the completion index.
Watch the Fed. Historically, these smaller companies are more sensitive to interest rates because they often carry more debt to fuel growth. With the Fed funds rate sitting around 3.75% as of late 2025/early 2026, keep an eye on how these companies manage their interest expenses.
Don't panic on red days. This index will drop harder than the S&P 500 when things get ugly. That’s the "volatility tax" you pay for the potential to catch the next Nvidia while it’s still a "small" company.
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The Dow Jones U.S. Completion Total Stock Market Index isn't just a backup dancer for the S&P 500. It’s the engine room. It’s where the future of the economy is being built, one $2 billion mid-cap at a time.