Forget the Plain S&P 500. The Momentum Version Captured the Run and Beat It by 15% This Year

MTUM has materially outperformed SPY in 2026, rising 30.52% year-to-date versus 10.34% for SPY, and also leads over 1-, 5-, and 10-year periods at 42.90% vs 27.13%, 104% vs 89%, and 391% vs 325%, respectively. The article argues that a momentum tilt has better captured the market’s AI-driven leaders, though MTUM charges 0.15% versus SPY’s 0.0945% and carries higher turnover and tax risk. The piece is broadly favorable to MTUM as a potential swap from cap-weighted exposure, but emphasizes account-type and whipsaw considerations.

Analysis

The real message here is not that momentum is “better” in the abstract; it is that the current market regime is unusually favorable to a concentrated leadership basket. When a few mega-cap platforms and AI enablers dominate both earnings revisions and index flows, a cap-weighted vehicle systematically dilutes the names with the strongest price/earnings momentum just as they are compounding fastest. That creates a second-order advantage for MTUM: it is effectively rebalancing into the same crowded winners that passive flows keep reinforcing, while SPY keeps funding underperformers that are still large enough to matter.

The risk is that MTUM’s edge is path-dependent, not permanent. Momentum tends to fail in sharp factor rotations, and the pain usually arrives over weeks to months, not years, when rates move, breadth broadens, or earnings leadership shifts from mega-cap growth to cyclicals/value. The semiannual rebalance cadence means MTUM can be late to both exits and re-entries, so the strategy is exposed to “whipsaw” if the market transitions from trend-following to mean-reversion before the next rebalance window.

A more interesting implication is for the underlying leaders themselves: if MTUM keeps receiving mechanical inflows, it creates an incremental marginal bid for NVDA, MSFT, and AAPL beyond broad-market demand. That can compress near-term volatility and extend the duration of the leadership trade even if fundamentals merely meet expectations. The contrarian view is that the crowd may now be overpaying for persistence; if consensus has already moved to “buy the winners,” the next 3–6 months may be defined by whether earnings growth broadens enough to justify cap-weighted ownership again, or whether momentum becomes too one-sided and vulnerable to a drawdown.

Key Decisions for Investors

• Rotate fresh equity exposure from SPY into MTUM on a 3-6 month horizon; target the swap in tax-advantaged accounts where the fee differential is negligible relative to expected factor alpha.
• For taxable accounts, avoid realizing legacy SPY gains; instead direct new contributions and rebalancing proceeds into MTUM, keeping the option to switch fully only if momentum leadership persists through the next rebalance window.
• Long MTUM / short SPY as a modest relative-value expression for the next 8-12 weeks; the thesis is continued concentration in AI/mega-cap leadership, with the main risk being a sudden breadth rotation or rates shock.
• Buy NVDA pullbacks rather than chasing SPY broad-market exposure; MTUM-style flows should continue to support the strongest momentum name, but size it with a tight stop because any earnings miss would hit the factor sleeve hardest.
• If you expect rotation risk to rise into the next 1-2 quarters, hedge MTUM longs with a small equal-notional short in QQQ or a call spread on SPY to protect against a sharp factor unwind while keeping upside to the leaders.