Amazon still owns the cloud. But earnings reports on Thursday from the e-retailer as well as rivals Microsoft and Alphabet show that the battle is in its early days and competition is fierce.

In a rare confluence of events, all three companies reported quarterly results on the same day, giving investors an abundance of data on the state of cloud computing:

Amazon Web Services is the clear leader and the only one of the three companies that provide a clean number for its cloud infrastructure business. Amazon said AWS revenue surged 43 percent in the quarter to $3.66 billion. Multiply that by four, and you get an annualized run rate of $14.6 billion.

Microsoft wraps its Azure business into a division called Intelligent Cloud, which includes various other servers and cloud services. In total, that business grew 11 percent to $6.8 billion. While Microsoft doesn't break out Azure's revenue, it does offer up a growth number. In the quarter ended March, sales jumped 93 percent. Microsoft also said that its full Commercial Cloud business now has an annualized run rate of $15.2 billion, but that business also includes Office 365, not just the Azure infrastructure service.

The Google Cloud Platform remains a laggard and is such a small portion of Alphabet that the company didn't even mention the business in its earnings release. Of Google's $24.5 billion in first-quarter revenue, $21.4 billion came from advertising. However, sales in the rest of the company jumped 50 percent to $3.1 billion, and a big part of that increase was clearly from new cloud-computing clients.

With more corporations, government entities and non-profits downsizing their own data centers in favor of the massive infrastructure operations controlled by the tech giants, all three companies are racing to land major contracts and attract developers by building cutting-edge tools.

"This space is an oligopoly," said Trip Miller, the founder of Gullane Capital Partners and an investor in Amazon. "No one else of any meaningful size outside a handful of major players is getting into it because they can't afford to get into it."

AWS's fingerprints were all over Amazon's earnings report, with the acronym showing up 44 times.

In addition to disclosing revenue and the unit's 24.3 percent operating margin, Amazon referred to a host of new AWS products like Amazon Chime for making online meetings easier and contact center technology called Amazon Connect. The company also said that AWS has regions opening up this year in France and China and that the cloud division "collaborated with NASA to deliver the highest resolution video ever broadcast live from space."

According to Synergy Research Group, AWS controlled 40 percent of the public cloud services market as of early February, compared to 23 percent for Microsoft, IBM and Google combined.