If only there were some easy metaphor to describe how SpaceX’s initial public offering took off today. Oh well.

Shares in the rocket and AI company ended their first day of trading up 19%. It’s the biggest IPO in history, making Elon Musk the world’s first trillionaire and minting some new billionaires too. But there’s a catch, and that’s where we’re starting off today’s newsletter.  — Tony Wagner, newsletter editor

The people who bought stock in SpaceX today are not the only ones who own a piece of that company — not even close. There’s a whole long line of people who got there first.

Elon Musk obviously owned shares of the company before anyone else did — he actually owns just under half of all SpaceX shares, hence his new trillionaire status. There are also venture capital firms, early investors, and employees who get shares as part of their pay.

“There are an awful lot of early investors in SpaceX who have made unimaginable returns in short periods of time,” said Lise Buyer, founder of IPO advisory firm Class Five Group.

A lot of them would probably love to sell on day one of trading to make some quick cash. But that would look really bad: “‘Hey, management is selling the shares, that’s not cool, don’t they believe in the company?’” said John Pennett, a partner at consulting firm Eisner Amper.

Not only would it spook new investors to see the old investors and higher-ups suddenly selling, it would also just take some of the air out of the entire IPO.

“Everybody starts to sell, which then starts putting a lot of downward pressure on the stock price,” Pennett said. Not to mention, insiders selling their shares on day one would sort of invite insider trading.

“When a company is going public, insiders in particular typically have some information that outside investors might not be aware of,” said Jay Ritter, director of the IPO Initiative at the University of Florida.

So, for all of these reasons, the original investors are contractually not allowed to sell their shares at first. It’s called a “lock-up period.” Ritter said they commonly last 180 days. But they could be 90 days, could be less.

SpaceX is releasing its original investors from selling-jail gradually: They can sell a little bit after the next earnings report, a little bit more if the stock is doing really well, a little bit more later. Basically, it’s a way to let investors and employees make some money without rocking the whole boat.

When “Marketplace Morning Report” went to Thomasville, Alabama recently, Just about everyone host Kimberly Adams met told her a story about how access to the local hospital helped them in a crisis. Nichole Stinson’s was particularly harrowing, even though Easton’s OK now.

That hospital Stinson took her son to closed a few years ago. The city has been working to reopen it, and grappling with economic ripple effects, to no avail. “Morning Report” spent all this week looking at how changes in federal policy show up in rural healthcare — and what that means for the economy wherever you are.

There’s only one trillionaire on the planet, and there are only about a dozen companies with market capitalization over $1 trillion. It’s so much money, most people can’t wrap their mind around it. Want proof? Try out this dead-simple but surprisingly hard game, then check out these charts to put the SpaceX IPO in perspective.