Sometimes the market is a tough crowd. Tempus AI (TEM) delivered a fourth-quarter earnings report on Tuesday that, on paper, looked pretty good. They beat revenue estimates. They met the consensus on losses per share. Their core businesses are growing fast. And yet, the stock decided to take a little trip south in after-hours trading.

Let's break down what happened. The company reported a loss of four cents per share, which was exactly what analysts were expecting. The real story, though, was on the top line. Revenue came in at $367.21 million. That wasn't just a beat against the Street's estimate of $362.29 million; it was a massive jump from the $200.68 million they reported in the same quarter last year. That's the kind of growth investors usually like to see.

So why the sell-off? It's one of those classic market puzzles. Maybe the guidance wasn't exciting enough. Maybe some investors were hoping for an even bigger beat. Or maybe it's just one of those days. The stock slid 4.14% to $55.55 after the bell, according to market data.

Digging into the details shows where the strength really was. The company's diagnostics business is on fire. That segment brought in $266.9 million in Q4, which is a staggering 121.6% increase from a year ago. The CEO, Eric Lefkofsky, pointed to volume growth as the driver: Oncology test volume was up 29%, and Hereditary volume grew 23%. Another promising area, MRD (minimal residual disease) testing, saw volume hit about 4,700 tests in the quarter, up 56% from the previous three months.

The other half of the business, Data and Applications, is also growing steadily. It generated $100.4 million in revenue, up 25.1% year-over-year. Within that, the Insights data licensing part grew 69.5%, if you exclude the impact of a one-time item related to AstraZeneca.

Lefkofsky sounded confident in the results. "In 2025, Tempus continued to set the standard for what it means to be a technology company operating in the health care space," he said. He added, "The strength of our unit growth in diagnostics along with the accelerating growth of our data business is proof that we are unique in this space."

The company also posted some impressive annual metrics. They finished the year with over $1.1 billion in Total Remaining Contract Value—essentially, revenue they've already locked in for the future. Their Net Revenue Retention rate was 126%, meaning existing customers are spending more over time, which is a very healthy sign for a subscription-style business.

Looking ahead, Tempus AI gave its outlook for fiscal 2026. The company expects revenue of about $1.59 billion. That's just a hair above the analyst consensus estimate of $1.58 billion. It's a solid forecast, but perhaps not the blowout number that would have sparked a rally after such strong quarterly growth.

In the end, it's a classic earnings story: great numbers on the page, but a stock price that tells its own, slightly more skeptical, tale. The market is always looking forward, and sometimes even a beat isn't enough if the future looks just a little too much like what everyone already expected.