The Best Growth Index ETF to Invest $100 in March 2026

Most of the time, index funds like the Vanguard Growth ETF (NYSEMKT: VUG) or the iShares Russell 1000 Growth ETF (NYSEMKT: IWF) are a smart, no-fuss way to invest a little bit of money (say $100, for example) in a long-term growth holding.

As it stands, however, these two particular exchange-traded funds (ETFs) both pose the same risk at the moment. That risk is the chance that the artificial intelligence (AI) bubble pops, pulling the rug out from underneath the stocks that make up far too much of both index funds' current values.

For perspective, Nvidia, Apple, and Microsoft currently collectively account for about 30% of each fund's total value. Adding Broadcom, Amazon, Alphabet, and Tesla to the mix pumps this number up to more than 50%. If these AI-focused stocks implode, it could devastate investors who thought they were better protected by exchange-traded funds' inherent diversification.

Fortunately, there's a way to avoid this very scenario. You should put that $100 investment toward the iShares MSCI USA Equal Weighted ETF (NYSEMKT: EUSA).

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This better-balanced portfolio could soon have its day in the sun

If you're not aware, most exchange-traded funds are cap-weighted, meaning the size of each individual stock position held by the fund is proportional to the size of the underlying company -- the bigger the company, the bigger the position. That's how the Vanguard Growth ETF and the iShares Russell 1000 Growth ETF became so dangerously imbalanced -- a small number of technology names have grown into massive companies.

The iShares MSCI USA Equal Weighted fund sidesteps this problem, though. Meant to mirror the MSCI USA Equal Weighted Index, it holds equally sized positions in every ticker it owns, rebalancing as needed every quarter if some of its holdings grow or shrink to become less than equal-weighted.

On the surface, it may not seem like an absolute must-do. While VIG or IWF may be poorly balanced now, at least they've benefited from the big run-up that a few large-cap technology names have experienced over the past three years. EUSA, conversely, consistently exits a portion of some of the market's best-performing stocks. And to be fair, that's part of the reason this fund has lagged during this stretch.

On the flipside, the past three years have been remarkably unusual. In a normal, better-balanced market environment, you can expect to see better performance from an equal-weighted fund.

Then there's the other nuance that nearly nobody appreciates enough at this time. That's the fact that mid-cap stocks typically outperform large caps. They've not done so lately, just because the aforementioned lot of large caps have done so well that they've carried the whole S&P 500 large-cap index higher with them. If this isolated leadership unwinds from here, though, don't be surprised to see mid-cap stocks step up as leaders again.

It matters simply because nearly half of the MSCI USA Equal Weighted Index's value comes from mid-cap stocks.

Enough growth in light of unknown risks

But it's not specifically a growth fund? That's OK. You'll still get the growth benefit of this ETF's holdings. You'll just be getting it every quarter rather than on a buy-and-hold basis, by virtue of locking in partial profits from any names that have experienced some gains. If you end up doing it over and over with the same few names, then so be it.

Mostly, though, this exchange-traded fund lets you keep that $100 in the overall market without forcing an uncomfortable amount of exposure to a small number of AI-centric technology stocks on you. Without any real certainty regarding what's next for the market, that in itself is huge.

James Brumley has positions in Alphabet. The Motley Fool has positions in and recommends Alphabet, Amazon, Apple, Microsoft, Nvidia, Tesla, and Vanguard Growth ETF and is short shares of Apple. The Motley Fool recommends Broadcom. The Motley Fool has a disclosure policy.