Sirius XM Radio (SIRI -4.93%) and Michael Kors (CPRI -2.42%) don't have a lot in common. Satellite radio and luxury handbags will rarely be mentioned in the same sentence. But both market darlings did something important this morning: Sirius XM and Michael Kors announced quarterly results in which they each topped $1 billion in revenue for the first time.

Analysts didn't think it would happen this soon at either company. They were banking on $981.9 million out of Sirius XM. The pros brutally underestimated the potential at Michael Kors, expecting the seller of high-end totes, satchels, and other fashionable accessories to ring up less than $860 million in sales. 

It's not a surprise that Michael Kors clocked in with the biggest of the two top-line beats. There's seasonality at play here, and it's easy to aim too low or too high in forecasting how fickle holiday shoppers will pan out. Michael Kors saw its revenue soar a whopping 59% during the period. It had grown its sales by 39% during the prior quarter, but why did analysts see holiday sales decelerating to 35%? The economy's getting better. Michael Kors is proving that it's growing at the expense of slower if not fading competitors. Accelerating revenue growth shouldn't have been a surprise, though no one saw $1 billion coming. No one even saw $900 million coming, as the highest top-line target among the 18 analysts tracking Michael Kors was $885 million.

The beat by Sirius XM wasn't as prolific, but it was equally as surprising. There was less mystery here. The satellite radio provider is growing slower and steadier. It told investors last month exactly how many subscribers it had at the end of the year, and analysts know that average revenue per user is inching higher with every passing quarter as a result of a price hike initiated two years ago. But even with so many of Sirius XM's cards on the table, the most ambitious of the dozen analysts publishing projections were calling only for $995 million in revenue.

The prognosis is good for both companies. Sirius XM should continue to grow, even though investors will want to keep an eye on the slight decline in conversions and the slight uptick in churn. Michael Kors isn't likely to stay in the 10 digits when it reports its revenue for the new quarter. Despite its stellar growth, there has historically been a sequential decline after the holiday shoppers move on.

It's still a great day for both companies. You never forget your first $1 billion quarter, even if you have to share it with a completely unrelated growth stock.