So, here's what happened with Shift4 Payments (FOUR) on Thursday: the stock took a dive. It wasn't a great day for the payments processor, which delivered a set of fourth-quarter results that were, well, mixed. The real kicker for investors, though, was a look ahead to 2026 that came in softer than expected.

Let's break down the numbers. For the quarter, gross revenue came in at $1.19 billion. That's a solid 34% jump from a year ago, but it just barely missed the analyst consensus estimate of $1.20 billion. Adjusted earnings per share followed a similar pattern: $1.60, which was a hair below the expected $1.62.

Now, it wasn't all bad news in the quarterly report. The business is clearly growing. Payments-based revenue hit $919 million, up from $772 million a year ago. Subscription and other revenues climbed to $145 million from $115 million. A key metric the company highlights—gross revenue minus network fees—surged 51% year-over-year to $610 million. End-to-end payment volume was up 23% to $59 billion, and adjusted EBITDA improved 48% to $304 million (though the margin dipped slightly to 50%).

But here's where the story pivots, and why the stock reacted the way it did. The company laid out its financial outlook for fiscal year 2026, and it was this guidance that really seemed to spook the market.

Shift4 expects gross revenue, excluding network fees, to land between $2.500 billion and $2.600 billion. That's a big number, but it's well below the analyst consensus estimate of $5.202 billion. For adjusted EPS, the company is forecasting $5.50 to $5.70, which is also below the Street's expectation of $6.47. On the brighter side, it projects end-to-end payment volume of $240 billion to $260 billion and adjusted EBITDA between $1.165 billion and $1.215 billion.

The company also gave a peek at the current quarter. For Q1, it expects gross revenue minus network fees to be close to $548 million, which is below the consensus estimate of $1.134 billion, and adjusted EBITDA to be near $233 million.

By the end of trading Thursday, Shift4 Payments shares were down 12.26% at $50.33, hitting a new 52-week low.