Three Accounts, One Bet: Why More Accounts Isn't More Diversified

I did this one myself for the better part of a decade. It was only after at least 500 hours of self-study and book-reading that it suddenly struck me: "I only am invested in stocks!"

I had my TSP 100% invested in the C Fund, three total stock funds in my brokerage account that had different ticker symbols but essentially the same holdings, and a self-directed retirement account investing in the S&P 500. Three accounts, three separate logins, three different tax treatments. I thought I was building a diversified position.

I was building one position, that was nothing more than very well organized.

Part 2 of our Whole-Life Portfolio series ended with a promise: which funds and accounts actually fill the roles your TSP leaves empty. Before we get there, we have to clear out a mistake sitting on the growth side of the house — because it's the one that convinces people they're diversified when they aren't.

Part 2 put the TSP in its place as your Reserve — the King on the board, guarded, not gambled. What nobody mentioned is that your Roth IRA and your brokerage account can quietly become two more pieces standing on the same square as the King, doing nothing the Reserve wasn't already doing.

The Four Core Missions (and the One That Rides Along)

Quick refresher, because the rest of this post depends on it. Every dollar you own is assigned one of four Core Missions:

Growth. Income. Liquidity. Preservation of Capital.

Inflation Protection isn't a fifth mission. Inflation is like the Fog of War, present always, not a separate objective, and every one of those four missions has to be evaluated through it. Growth that doesn't beat inflation isn't growth. Income that doesn't rise with your grocery bill isn't income. You ask, of every dollar you own: does this still do its job once inflation gets a vote?

Hold onto that. It's about to do real work in the second half of this post.

Why We Say 100% C Fund

Most military financial content will hand you an allocation formula: some C, some S, a little I, adjust with age. It sounds sophisticated, and in an attempt to feel sophisticated you might chase tiny percentages here and there, but make no real progress. It's basically just a shell game, and a false sense that the spreading-around accomplished something. Naturally this sort of balancing act is a real strategy and does add diversification, but just because you know you should be doing it generally doesn't mean you need to do it in the TSP.

Our recommendation for the overwhelming majority of TSP investors is simpler: 100% C Fund. Here's why.

The I Fund isn't international.

Since September 2024 the I Fund has tracked an index that deliberately excludes China and Hong Kong. That is roughly 7% of the entire non-US investable market, carved out by design, and that is a painful exclusion. In 2024, MSCI China returned 19.67% while the I Fund returned 5.36%. From 2024–2025, China compounded to roughly 57% against 15.6% for the I Fund (source: tsp.gov/share-price-history). Looking forward, Goldman Sachs projects MSCI China climbing roughly 20% through the end of 2026, and Morgan Stanley carries a comparable 14% target. Treat any 12-month Wall Street target with the skepticism it has earned, but when two of the largest research shops on earth have meaningful upside as their base case, "this fund deliberately avoids that market" is a cost you're paying, not a safety feature you're getting. If you really don't like China personally, then by all means invest in the I Fund — but if your mission is to maximize retirement wealth, sell it now.

The S Fund isn't small-cap.

It tracks the Dow Jones U.S. Completion Total Stock Market Index, which is exactly what it sounds like: everything in the U.S. market that isn't in the S&P 500. Look at what actually sits at the top of it — Snowflake, Marvell Technology, Cloudflare, MicroStrategy, Roblox. Those aren't sleepy small companies waiting to be discovered. They're high-beta technology and crypto-adjacent names, and when the market sells off growth, they fall harder than the C Fund does, not softer. As a hedge against your C Fund, the S Fund fails. It's the same trade with the volume turned up.

The work nobody actually does.

And there's a third reason nobody says out loud: allocating across C, S, and I properly — tracking benchmark changes, valuation spreads, currency effects, rotation timing — is work almost nobody actually performs. Not because you're incapable. Because you have a job, and it isn't portfolio management. Should the average investor think that way? Yes. Will they? No. A strategy that only works if you do homework you're never going to do isn't a strategy. It's a wish.

The C Fund is 500 of the largest companies in the world's largest economy, at 0.035% cost. That means it costs $350 per year for every $1 million invested. Basically free — and cheaper than any fund you find elsewhere. Set it, contribute relentlessly, and go do your actual job.

So When Does the Roth IRA Earn Its Keep?

Here's the part that surprises people. The main reason to run a Roth IRA alongside your TSP on active duty isn't tax treatment: you can already get Roth treatment inside the TSP.

It's that the Roth IRA is where you execute the trades the TSP can't do well.

If you develop genuine conviction that international belongs in your portfolio, a Roth IRA lets you buy a real total-international fund, one that doesn't carve out China and Hong Kong, and doesn't make you accept someone else's foreign policy as your asset allocation. If you believe small caps are due, you can buy an actual small-cap fund instead of a completion index topped by Marvell and MicroStrategy. And if you conclude that expensive U.S. large-cap is about to hand the baton to cheaper equities, you have somewhere precise to act on it.

That's the division of labor. The C Fund is the only fund the TSP offers that fits a core niche in your strategy without compromise, performs at a high level, and successfully executes the Growth mission for your plan. For the other elements of a diversification strategy for retirement, the Roth IRA is where conviction gets executed properly. Yet that still doesn't mean you should.

Three Accounts. Every Box Checked. But Completely Exposed.

Let's return to the household from Part 1, two years down the road. Everything has gone well.

The TSP has grown from $150,000 to $180,000. The Roth IRA is up from $40,000 to $50,000. The brokerage has climbed from $60,000 to $72,000, still index funds. And the HYSA — earning about 4% the entire time, because that's what a High Yield Savings Account does — has grown from $30,000 to roughly $32,448.

Total household wealth: $334,448. Of that, $302,000 — just over 90% — is equities. Notice that because of higher returns to the stocks, their concentration gets worse and their risk increases over time. When the market falls, it does not matter that the exposure is spread across a TSP, an IRA, and a brokerage. Every account drops together, on the same day, for the same reason.

Run the numbers on an ordinary correction. A 20% drop takes $60,400 off this household. A 30% drop — the kind that shows up two or three times in a working life — takes $90,600, and the portfolio drops through the clouds with a hard landing at $243,848.

Here's the line I want you to sit with: the only real Asset Allocation in this entire Whole-Life Portfolio is the HYSA, and it's under 10% of the total. That $32,448 is the sole position doing something different from everything else. It is the only dollar that doesn't move when the S&P moves. Ten percent of this family's wealth is holding the line for the other ninety.

That's not a portfolio. That's a single bet with a small cash buffer stapled to the side.

What Actually Fills the Gap

First, let's be very clear: it is no longer a bond strategy that Wall Street, your parents' money manager, and your Aunt Mathilda try to sell you. Since the massive policy shifts in US policy in 2008 and again in 2020, bonds stopped doing what they used to do, and instead have traced stocks: down when stocks are down, not executing Preservation of Capital.

So in the TSP it is not the F and G Funds. Over the past decade the G Fund returned 2.89% annually and the F Fund returned 1.63%. Inflation over that same decade averaged 3.33%. Both funds lost purchasing power — the F Fund by nearly two points a year — which means they failed the inflation test, and failed the Preservation of Capital mission. Meanwhile a High Yield Savings Account or Money Market Account (MMA) today pays in the neighborhood of 4.00% to 4.50%, and does it with FDIC or NCUA insurance protecting up to $250,000 per depositor, per institution. Equal or higher return, government-backed protection against loss, and you can reach the money the same day. The F and G Funds offer none of those three things better. Preservation of Capital is a real mission. The TSP is not where you go to accomplish it.

If you noticed, the HYSA and MMA also provide Liquidity: holding responsible levels of cash in an inflation-protected account literally does triple duty: preservation, liquidity, and inflation protection!

And there are still other options for achieving the Preservation of Capital mission while defending against inflation, and this is where your Roth IRA can do meaningfully better: it holds things the TSP has never offered. A gold ETF is the clearest example — an asset with low-to-negative correlation to the stock market, meaning it has historically tended to hold its value or rise precisely when equities fall. That isn't a different flavor of stock. That's a genuinely different asset, performing a job no TSP fund can perform.

Your after-tax brokerage is where the real breadth lives. If it holds the same U.S. large-cap index funds as your TSP and your IRA, you haven't diversified — you've bought your existing bet a third time, in the least tax-advantaged wrapper available. Use it for what the other two can't reach:

• Money Market Accounts and Treasuries for the liquid, protected slice.
• Gold and broad commodity funds.
• Energy, alternatives, and derivatives strategies accessed indirectly and sensibly through sector and commodity funds rather than by trading them yourself.

These are the positions that don't move when the S&P moves — which is the entire point.

And similar to an after-tax brokerage, you can also open non-retirement accounts to invest in other asset classes and alternative assets. They function like a brokerage — you fund them, you hold positions, you can access the money — but each is specific and unique to a single asset class the public markets don't reach well.

• E-REIT platforms like Fundrise or Streitwise put you into commercial and residential real estate without buying a building.
• Debt-based crowdfunding platforms like Prosper let you hold consumer loans and collect the interest a bank would otherwise collect.
• Masterworks fractionalizes blue-chip fine art.

You do not need all of them, and none of them belongs in your first $10,000. But every one of them holds something that has no idea what the S&P 500 did today, and that independence is precisely the characteristic your portfolio is missing. That low or reverse correlation is what buys you Preservation of Capital. Then just run all of it through the same screen: does it still do its job once inflation gets a vote? Now you're starting to build a real portfolio for your wealth!

Where This Goes Next

The mistake in this post isn't owning stocks. Equities are a legitimate engine for the Growth mission, and the C Fund is the most efficient one most Service Members will ever be handed. But they are one tool among several — and for a lot of military families, leveraged real estate builds wealth faster than any index fund will, precisely because the bank funds most of the position and your tenant pays it down.

The mistake is thinking that three accounts holding the same thing constitutes a plan, and then discovering during the correction that ninety percent of your life's savings has gotten decimated.

Part 4 finishes moving your Wealth Task Force into position — the Main Effort (cash, your Queen) and Air Power (real estate) — starting with the mission this series has been circling from the beginning: Liquidity. Why cash is a position and not a failure to invest, why the wealthy hold so much more of it than you'd expect, and how the assets you buy for retirement — starting with real estate — can start paying you before you retire. Then a look back at how the whole board fits together now that every mission finally has an owner.

This content is educational in nature and does not constitute financial advice. Specific platforms are named as illustrations of asset categories, not as recommendations or endorsements. You are responsible for your own financial decisions. When in doubt, consult a licensed financial professional.

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