Many people think that they ring a bell at the top of a bull market. Ding-a-ling-a-ling.

That is indeed often the case. The bell was rung in 2000 at the top of the dot-com bubble — I like to think it was 3Com spinning off Palm that broke its back.

But sometimes there is no bell, no catalyst, no story to tell. A bull market becomes a bear market, and it happens just like that.

Silicon Valley has been in a food fight for about three years now. Everyone knows it’s going to end, except for the folks in Silicon Valley. These guys are funny. I met a few of them in the last cycle. They really thought it was going to go on forever.

There are now 145 unicorn companies (private companies with a valuation of $1 billion or more), with a total combined valuation of $506 billion.

We are watching the top happen right before our eyes.

Square

If you were paying attention a couple of weeks ago, you might have read the news about a company called Square going public. Jack Dorsey is the CEO of Square. He is also the CEO of Twitter. I think of this sometimes whenever I complain that I’m too busy.

Square got a round of financing in 2014 at a $6 billion valuation, and now it’s a public company. If you pull up SQ on Yahoo! Finance, you will see that the market cap is $4 billion.

As Square was making the rounds in the roadshow, investors decided they didn’t want to overpay just to make the mezzanine round investors rich. So there wasn’t much demand for Square at a $6 billion market cap. It eventually went public at a $3 billion market cap, or $9/share. (The deal performed well in the aftermarket, at least. The stock is trading at $12.)

No catalyst. No bell ringing. The price simply got too high, and people pulled back. But you know what this means. If one deal can trade below private valuations, they can all trade below private valuations.

On to the next data point…

Fidelity

You may not know this, but Fidelity owns shares of private companies in some of its funds (like Contrafund). Fidelity has to figure out how to value these things.