The Blackstone Group LP

Everybody loves exchange-traded funds (ETFs) these days.

There are a mind-boggling 2,000 ETFs, give or take, in the United States today. Roughly 70% of those are equity funds.

The three largest equity ETFs, packed with around 25% of all equity ETF assets, are S&P 500 index funds, like the SPDR S&P 500 ETF Trust.

Now, it's true that indexing gets most of the investment love at the moment, but there's a really brisk business in so-called "motif" or "thematic" passive strategies.

These let investors tap into just about any sector or idea that strikes their fancy.

Of course, you can passively invest in exciting sectors like robotics, defense cybersecurity, or biotechnology, but you can also buy ETFs that invest in faith-based or special-value principles, like veganism (I'm serious) and animal welfare, or social justice.

Essentially, here in the weird year 2018, if an investor can fathom it, there is an ETF that can be created to allow for one-click investing in the idea.

But ultimately, most of the money is flowing into the large-cap indexes.

After all, indexing is the new pet rock/Rubik's Cube/Beanie Baby, and, as such, is the answer to all our investing prayers.

Wall Street is embracing the idea that the unmanaged indexes will usually outperform the highly paid active managers.

Faced with the prospect of collecting low fees, or worse, no fees, even the old-school brokerage and investment management firms are pushing the idea of low-cost index funds to their clients.

It is the ultimate solution (to a problem nobody really has). Like party drugs, nobody can get enough of these things.