Reuters ran a piece this week answering a question a lot of ordinary investors are quietly asking: what do the giant IPOs supposedly coming, Anthropic, SpaceX, OpenAI, do to my money? The short answer from the experts they spoke with is that these offerings may already be touching your portfolio, whether you've noticed or not. You can read the full piece here.

This sounds like a subject that only concerns hedge funds and pre-IPO insiders. It doesn't, so it's worth going through the mechanics.

When a company goes public, index funds buy it. That's not a decision, it's arithmetic. The cleanest example is a total market index: once a company is publicly traded, a fund tracking the whole market picks it up automatically. The S&P 500 is fussier. Inclusion there comes with seasoning and profitability requirements, and as Reuters notes, companies like these may not clear those bars right away, or for a while. But if you own broad index funds, you don't do anything when a giant finally lists. Your fund does the doing. So when a company the size of OpenAI or SpaceX eventually trades publicly, tens of millions of retirement accounts could own a slice of it, most of them without ever knowing the company's name appeared on a statement.

The second channel is more subtle: money has to come from somewhere. A huge IPO absorbs capital. Investors who want the new hot listing often sell something else to fund the purchase, which can put quiet pressure on existing holdings. If a $500 billion company lists and the market doesn't grow by $500 billion overnight, other things likely get trimmed at the margins. Not a crash, and usually not even a correction. Just a reshuffling you'd never detect in a monthly statement.

There's also the valuation question, and regular readers know I have a bee in my bonnet about this. The bigger the share of the market that consists of newly public, richly priced companies, the more your index fund's overall valuation stretches. I've written before about the S&P 500 trading near dot-com-era multiples. Big IPOs, if they price at the rich multiples recent AI listings have commanded, don't fix that. They add to it. Nobody knows what these companies will actually charge for their shares, because nobody has filed a prospectus yet.

Now, the caveats, and there are a couple worth stating plainly.

First, none of these companies has actually listed yet. SpaceX has no IPO date. OpenAI has no IPO date. Anthropic has no IPO date. Talk of these offerings has been circulating for so long that the projections have taken on a strange life of their own; I've lost count of the "$1,000 into SpaceX" pieces I've had to gently pour cold water on. Until there's a prospectus and a ticker, this is a weather forecast, not weather.

Second, even when they do list, the effect on a diversified investor is likely to be modest. If you own a total market fund, a new entrant is one company among thousands. It will matter far less than whether you kept contributing through the next downturn, which brings me to the point I'll keep making until they wheel me out of here: patience and consistency beat positioning every time. The dot-com IPO wave of 1999 is the history lesson here. The companies that listed at absurd prices mostly deflated. The investors who held boring, broad funds through the whole mess did fine.

Third, some of the anticipation around these IPOs may already be reflected in funds that hold pre-IPO stakes in private companies. So if you're buying an actively managed fund today specifically to catch the Anthropic listing, you may be paying twice for the same optimism.

What should you actually do? In my view, nothing dramatic. If you own broad index funds, you'll participate in these listings automatically, at market price, with no effort, which is the whole beauty of the thing. If you're tempted to buy on day one, remember that newly public stocks are volatile, lockup expirations loom six months out, and the first year of trading tells you almost nothing about the tenth.

The IPO wave will come, or it won't, on its own schedule. Your plan shouldn't care either way.

As always, this is my perspective, not professional financial advice. Talk to a qualified advisor about your own situation.