After closing the day for a small loss during ordinary trading hours, shares of food delivery service GrubHub (NYSE:GRUB) bounced hard in after-hours trading, rising more than 5%.

Heading into earnings, analysts had forecast that GrubHub would report about 22.2 million "active diners" using its services in the fiscal fourth quarter 2019, and collect revenues of about $325.3 million. As it turns out, GrubHub did quite a bit better than that.  

Hand bearing platter of sandwiches emerges from a laptop

Image source: Getty Images.

Active diners hit 22.6 million in Q4, up 28% from last year's Q4 and up 7% sequentially from Q3 2019. Revenue rose 19% year over year to $341.3 million.  

The company's internal metric for measuring how often "active diners" are actively using the service, "daily average grubs," or DAGs, increased 8% year-over-year to 502,600. (That's the number of meals the company was delivering from restaurants to consumers on a typical day.)

Despite all this good news, and all this activity, GrubHub still failed to earn a profit for the quarter. Net losses as calculated according to generally accepted accounting principles (GAAP) were $0.30 per diluted share, a loss five times as bad as the $0.06 per share lost in Q4 2018.

For the full year fiscal 2019, active diners increased 28%, DAGS grew 13%, revenues were up 30% (to $1.3 billion) and the net loss was $0.20 per share -- meaning that it was Q4's performance that actually pushed GrubHub into a loss for the year.

Still, investors are treating the news as a win for GrubHub. That's the power of low expectations.