When investing in exchange-traded funds, less is more.

"Who is supposed to buy all these products?" I sometimes wonder when I browse the list of newly listed exchange-traded funds (ETFs). More than 2,000 ETFs with increasingly specific investment themes are now available on the Swiss stock exchange alone.

No, I wasn't eagerly awaiting the ability to choose maturities when buying US Treasury ETFs; that is, to have the option of choosing between 1 to 3 years, 4 to 7 years, and 7 to 10 years. I don't even want to hold Treasuries. And by the time the tenth ETF with European arms companies launches, this investment theme will surely be pretty saturated.

Sometimes I think that we need another stock market crash that truly deserves the name in order to curb the rampant proliferation of products.

But I initially thought a fund recently launched by UBS might be useful. The ETF tracks the MSCI USA Ex-Mega-Cap Specified Index. In other words, this product allows investment in the US stock market while excluding giant companies like Nvidia, Microsoft, and others. The largest holding in the ETF is the energy company Exxon, with a weighting of approximately 1.5 percent.

This way, one can reduce the concentration risks emanating particularly from the "Mag 7," the seven largest tech companies. But shouldn't good diversification also include Nvidia, Microsoft, and the like—simply with much less weighting than their actual market capitalization? Yes, of course. In short: A US ex-mega-cap product may serve a purpose for professional investors like pension funds or insurance companies—but I see no use for it myself.

In my opinion, one of the best innovations in ETFs is still those products that allow investment in equally weighted indices. This means that Apple shares have exactly the same weight as shares of Nike or Starbucks. All major ETF providers now offer such equal-weight products.

They make investing easy again, because with just two or three equity ETFs you can create a superbly diversified portfolio – in which neither US stocks nor the big tech companies are dominant.

My favorite product is the MSCI World Equal Weight index. It contains around 1,300 stocks from companies in 23 developed countries. The equal weighting mechanism automatically ensures a sensible country composition: US stocks make up a good 40 percent – ​​and not 70 percent as in conventional indices.

Of course, I would supplement this index, which contains just over 3 percent Swiss stocks, with an ETF focused on domestic securities: specifically, a product that tracks small and mid-cap stocks, for example, the SMIM or SPI Mid-Index. This guarantees no overlap with the MSCI World, which includes the shares of large companies. As a finishing touch, I'd add an emerging markets ETF, and that's it.