SPMO ETF 10-Year Backtest: How Momentum Crushed Both Diversified Portfolios and the S&P 500

$10,000 invested ten years ago. Three different strategies. Three wildly different outcomes: $24,638 in a diversified portfolio, $35,471 in the S&P 500, and $48,778 in SPMO. The gap is staggering.

When I first ran these numbers, I double-checked them. A momentum ETF nearly doubling the return of a textbook diversified allocation? It seemed too good to be true. But the data holds up. Today, I want to walk through each of these strategies side by side and share what I think these results actually mean for real-world portfolio decisions.

Why This Comparison Matters

There is an ongoing debate in the investing community that never quite resolves itself. One camp says diversification is the only free lunch. Another says just buy the S&P 500 and forget it. And a growing third camp argues that factor-based ETFs like SPMO can systematically outperform.

Each side has compelling arguments. But arguments are not evidence. A 10-year backtest provides the kind of extended track record that filters out short-term noise and reveals the true character of each strategy.

Option A: The Diversified Portfolio — Safety by the Book

The diversified portfolio tested here follows a classic allocation: 48% VTI (total U.S. stock market), 8% VNQ (real estate), 24% VXUS (international stocks), and 20% BND (bonds). It is the kind of portfolio a financial advisor might recommend for someone seeking balanced exposure.

Over ten years, $10,000 grew to $24,638. That is roughly a 9.4% annualized return, which is perfectly respectable by historical standards.

The real story, though, is in the downside protection. The worst year saw only a -8% drawdown. Compare that to -17% for the S&P 500. When markets were crashing, the bond allocation and international diversification served as shock absorbers.

The best year delivered a 24% gain. Not flashy, but consistent.

Here is the uncomfortable truth about this portfolio, though: that 24% allocation to VXUS was a significant drag over the past decade. International stocks, particularly in Europe and emerging markets, substantially underperformed U.S. equities. The diversification that was supposed to reduce risk also reduced returns, perhaps more than necessary.

For investors nearing retirement or those who cannot stomach large drawdowns, this kind of portfolio still makes sense. But for younger investors with long time horizons, the opportunity cost was very real.

Option B: The S&P 500 — Elegant Simplicity

Warren Buffett has said it. John Bogle said it. And the numbers confirm it: just buying the S&P 500 and holding has been extraordinarily effective.

$10,000 became $35,471. That is approximately 13.5% annualized — enough to outperform the vast majority of actively managed funds over the same period.

The best year brought a 31% return. The sheer dominance of U.S. large-cap stocks over the past decade is hard to overstate. Technology giants drove much of this performance, and the S&P 500 captured it fully.

But there was a cost. The worst year delivered a -17% decline. On a $100,000 portfolio, that is $17,000 evaporating. In theory, long-term investors should be able to ride it out. In practice, that kind of drawdown triggers panic selling for a significant percentage of people.

The S&P 500 strategy's greatest asset is its simplicity. No rebalancing decisions, no allocation debates, no second-guessing. You buy one ETF and you are done. That simplicity is not a bug — it is a feature. Complex strategies introduce decision points, and every decision point is an opportunity for behavioral mistakes.

Option C: SPMO — Momentum's Stunning Edge

SPMO, the Invesco S&P 500 Momentum ETF, selects stocks within the S&P 500 that have the strongest price momentum. The premise is straightforward: stocks that have been going up tend to keep going up, at least for a while.

The results speak for themselves. $10,000 grew to $48,778. That is 37% more than the S&P 500 and nearly double the diversified portfolio.

The best year produced an extraordinary 46% return. When momentum is working, it works spectacularly. The strategy concentrates capital in the market's strongest performers, amplifying gains during bull runs.

Here is the part that surprised me most: the worst year was only -10%. That is less than the S&P 500's -17%. Intuitively, you might expect a more aggressive strategy to fall harder during downturns. But momentum strategies naturally rotate away from declining stocks. As a stock's price weakens, its momentum score drops, and it gets removed from the portfolio. It is a built-in risk management mechanism.

This does not mean SPMO is without risks. The expense ratio is higher than a plain index fund. Momentum crashes — sudden reversals where previous losers outperform previous winners — are a documented phenomenon. And there is always the question of whether a factor that has worked for ten years will continue to work for the next ten. Past outperformance can attract crowded trades, which may erode future returns.

10-Year Backtest Comparison

Metric	Diversified Portfolio	S&P 500	SPMO
Starting Investment	$10,000	$10,000	$10,000
Ending Value	$24,638	$35,471	$48,778
Best Year	+24%	+31%	+46%
Worst Year	-8%	-17%	-10%
Strategy Complexity	Medium	Low	Low
Rebalancing Required	1-2x/year	None	None (internal)

What to Actually Do with This Data

On pure performance, SPMO wins decisively. But investment decisions should never be made on returns alone.

The diversified portfolio makes sense if you are within ten years of retirement, your portfolio represents a major portion of your net worth, or you know that large drawdowns would cause you to sell at the worst time. That -8% worst case is genuinely valuable. Consider, however, adjusting the international allocation downward if U.S. markets continue their structural advantages.

The S&P 500 makes sense if you want maximum simplicity with strong returns. Achieving 13.5% annualized with zero effort is a remarkable outcome. Most professional fund managers cannot match it. If you tend to overthink your investments, this might actually produce the best results precisely because it removes the temptation to tinker.

SPMO makes sense if you have a long investment horizon, you understand that momentum can underperform for stretches, and you will not panic-sell when the strategy lags the broader market for a quarter or two. A practical approach is to use it as a satellite allocation — perhaps 10-20% of your equity exposure — rather than going all-in.

Personally, after analyzing this data, I increased my SPMO allocation to about 15% of my portfolio. But the core remains in the S&P 500. A backtest is a rearview mirror, not a crystal ball. Whatever strategy you choose, it needs to match your risk tolerance and life circumstances. The worst investment strategy is one you abandon halfway through because you could not handle the volatility.