Cathie Wood's Biggest Buy Last Week Was SpaceX. She Sold Almost Exactly That Much Palantir the Same Day.

Cathie Wood's ARK Investment Management bought 205,031 shares of SpaceX (NASDAQ:SPCX) on Friday, a purchase worth about $27.5 million spread across four of its funds, according to ARK's daily trade disclosures. It was the firm's largest disclosed buy of last week.

The same day's file shows the opposite trade. ARK sold 156,110 shares of Palantir Technologies (NASDAQ:PLTR) for about $27.2 million -- its third sale of the artificial intelligence (AI) software specialist in five days.

Of course, ARK reports trades, not reasoning, and its disclosures say nothing about whether one trade funded the other. What they document is the pairing itself: about $27 million in and about $27 million out, on the same day.

Even so, I think the pairing is informative. On one day, Wood's firm moved about $27 million toward the rocket and AI infrastructure company trading near its offering price -- and about the same amount away from the software stock priced at more than 150 times earnings.

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The buy: SpaceX near its IPO price

The SpaceX purchase ran through four funds, with the biggest slice going to the flagship ARK Innovation ETF. And it lands in a portfolio that already leans hard on the name.

ARK Innovation held about 2.8 million SpaceX shares as of Friday, a position worth about $385 million (the fund's third-largest holding, at about 5.8% of assets). In ARK's autonomous technology fund, the stock ranks second, at more than 7% of the portfolio.

What makes the timing notable is the price. SpaceX priced the largest initial public offering (IPO) on record at $135 per share in June, traded as high as $225.64, and sits near $137 as of this writing. That is roughly back where it started, about 39% below the high.

The business has kept growing through the round trip. Second-quarter revenue rose 92% year over year to $7.81 billion, and the company signed $14.1 billion in cloud computing contracts during the quarter. Buying near the offer price gets Wood the same company the IPO's buyers paid up for, months of growth later.

The sale: a third trim in five days

The Palantir sales extend a pattern that has run for weeks. ARK sold the stock twice earlier that week, according to its disclosures, and it has been selling into strength ever since Palantir's second-quarter report sent shares up 29% in a single day earlier this month.

Even so, this is trimming, not exiting. Across ARK Innovation and its autonomous technology and next-generation internet funds, Palantir remains a position worth about $350 million combined, including about $209 million in ARK Innovation alone.

After all, the stock has given her plenty to trim from. Palantir trades near $177 as of this writing, up about 40% from where it sat before that August report. And the second quarter behind the move was extraordinary. Revenue grew 93% year over year to $1.94 billion, net income reached $1.06 billion (a 55% profit margin), and management raised its full-year revenue outlook to about $8.15 billion, which implies 82% growth over 2025.

The price of that performance is the sticking point. At a market capitalization of about $425 billion, Palantir costs about 154 times earnings, among the most expensive valuations of any large company on the market.

A relative call

So what does the pairing say? Wood doesn't seem to be souring on AI, since both companies sit at the center of the theme. And she isn't abandoning Palantir's business, which her funds still own in size.

The trades are ranking prices, not businesses. One company has nearly doubled its revenue over the past year and trades about where its record-setting IPO priced it. The other has been growing about as fast, but the market has already paid its stock for that growth, at more than 150 times earnings.

I'd read Friday's file as a price call, and the logic arguably holds together. But it is worth being precise about what the cheap side of this pairing costs. SpaceX's market value is about $1.9 trillion, or roughly 60 times revenue on an annualized second-quarter basis, and the company still runs at a loss. The buy makes sense as a relative call, and I think the ranking is right. But a relative call is all it is. Both stocks are still priced for years of growth that hasn't happened yet.

Daniel Sparks and his clients do not have positions in any of the stocks mentioned. The Motley Fool has positions in and recommends Palantir Technologies. The Motley Fool has a disclosure policy.