Amazon.com Inc. brought in $3 billion in profit thanks to record-breaking holiday sales, according to a Thursday earnings report, but a prediction of slowing growth may have kept its stock from reaping the rewards.

The online retailer reported fourth-quarter earnings of $6.04 a share on revenue of $72.4 billion Thursday afternoon, both quarterly records for Amazon AMZN, +5.69% , and strong increases from the 2017 holiday-shopping season, when the company reported $3.75 a share on sales of $60.5 billion. On average, analysts expected earnings of $5.65 a share on revenue of $71.88 billion, according to FactSet. It was the second consecutive holiday quarter that Amazon beat estimates, after not having done so since 2009.

Amazon shares did not receive a big bump from the beat, however, with the stock falling about 1% following the announcement and moving lower during a subsequent earnings call Thursday afternoon. Shares were down about 4% in early trade Friday.

One cause for the decline could be downbeat guidance for the first quarter, when Amazon expects revenue of $56 billion to $60 billion; analysts on average expected first-quarter revenue of $60.83 billion ahead of the report, according to FactSet. Executives on the conference call also noted that Amazon will likely increase spending faster in 2019 than it did in 2018, when a slowdown in spending added jet fuel to Amazon’s profitability — the company reported annual net income of more than $10 billion in 2018, up from $3 billion in 2017.

“In a lot of ways, 2018 was about banking the efficiencies of investments in people, warehouses, infrastructure, that we had put in place in 2016 and 2017,” Chief Financial Officer Brian Olsavsky said. “So while we will continue to concurrently drive growth and customer offering and Prime benefits, we certainly do take costs seriously and we will continue to work on operational efficiencies, I would expect investments to increase relative to 2018.”

Amazon has already announced plans to open new campuses in the New York and Washington, D.C., regions after a prolonged search for a second headquarters. Olsavsky reiterated that Amazon plans to spend $5 billion on those efforts and hire 50,000 employees, as well as hiring 5,000 people in the Nashville, Tenn., area for a new operations center.

For more: Why Amazon’s ‘HQ2s’ won’t create two more Seattles

The first-quarter forecast would produce revenue growth of 10% to 18%, after Amazon recorded a sales increase of 20% in the fourth quarter. Some analysts believe Amazon is entering a period of lower growth rates, as it attempts to revive growth at its Whole Foods Market grocery chain and as it continues to look for new international markets that may not produce immediate benefits.

“Our new numbers reflect the softer international economic landscape, particularly in Western Europe, along with a greatly reduced outlook for growth at Whole Foods, which we see as facing both increased competition and potentially some brand loyalty issues,” Benchmark analyst Daniel Kurnos wrote in a note this week while lowering his price target on the stock to $2,000 from $2,100.

Amazon reported that sales in physical stores fell 3% in the fourth quarter from the prior year, from $4.52 billion to $4.4 billion. Beyond Whole Foods, Amazon also operates physical bookstores and convenience stores, and opened some pop-up stores around the holidays to sell gifts popular on its website, including its own offerings like the Alexa-based Echo line of speakers.

For more: Amazon plans to expand reach of its Whole Foods stores

On the call, Olsavsky noted that Whole Foods numbers were affected by outside forces. He mentioned that a change to Whole Foods’ fiscal calendar to match Amazon’s added five extra days to the prior year’s fourth quarter, and that online Prime orders that are picked up at Whole Foods do not count as physical store sales. When adjusting for those factors, Olsavsky said, sales increased 6%.

“Whole Foods Market sales grew approximately 6%, and we’re very pleased,” an Amazon spokeswoman said in an emailed statement.

Amazon also is seeing increasing sales from third-party sellers on its marketplace, which brings down net sales, according to Wedbush analyst Michael Pachter.

“Because Amazon reports only fees (estimated 30% of GMV) from third-party sales, a higher mix of third-party lowers reported revenue without impacting EPS,” Pachter wrote ahead of the report.

Amazon noted in its report that more than 50% of sales on the platform came from small- and medium-size businesses in the fourth quarter. On the call, Olsavsky suggested that Amazon could consider changing the fee structure it charges sellers in response to these issues.

“More than half of our units sold are from third-party sellers, so it’s very important to us that we have the right business profile both for Amazon and for the sellers. So we will always be evolving that,” the CFO said. “Part of that involves changing fee structures, sometimes adding new fees or subtracting old ones, part of it involves raising or lowering fees that sellers pay. So you’re going to see this continually from us.”

See also: The engine for Amazon earnings growth has nothing to do with e-commerce

Amazon Web Services, though, continued to be Amazon’s profit and growth engine. The cloud-computing arm reported sales growth of 45%, to $7.43 billion from $5.11 billion, and operating income that increased 61%, to $2.18 billion from $1.35 billion.

Amazon also continued to benefit from massive growth in its advertising business. The company reported revenue of $3.39 billion in its “Other” segment — largely advertising sales, though it also includes other services offerings — for year-over-year growth of 95% from sales of $1.74 billion. For the full year, Amazon reported more than $10 billion in revenue from the advertising and other services segment, more than double the roughly $4.65 billion reported in 2017.