Amazon Web Services (AWS), Microsoft, IBM and Google are blazing a trail as the “Big Four” leaders in cloud infrastructure services, seizing control of over half the market, according to a new report from Synergy Research Group.

The research outfit compiled second quarter earnings data that suggests the big four have boosted their dominance of an overall Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and private cloud market that’s worth some $6 billion per quarter. The companies counted aggregated revenues of more than $3 billion between them, Synergy Research said.

“The rest of the market is being left behind. No other company has been able to get close to these four in terms of data center footprint, global presence and market power,” John Dinsdale, Synergy’s chief analyst, explained.

Synergy’s report contrasts the position of the big four now with 2013, when they controlled just 41 percent of what was a $2.5 billion market in Q2. Over the last year, the big four cloud companies have seen revenues grow by a whopping 84 percent, giving them 54 percent of the total market for cloud infrastructure services in Q2 of 2015.

Is it a “Big Four” or a “One-plus-Three”?

Synergy might claim the cloud is dominated by a “Big Four”, but one can’t help but look at the numbers and wonder if it’s really a “Big One” plus three challengers. Going by Synergy’s numbers, AWS is way out in front of the others, owning 29 percent of the total market in Q2 of 2015, up from 25 percent in the same quarter of 2014.

That’s more than two-and-a-half times the share of second-place Microsoft, which currently owns 12 percent of the market, up from 9 percent one year ago. Rather surprisingly, IBM beats out Google to third place, with a seven percent share of the market thanks to its hybrid solutions. Meanwhile, Google controls a rather puny six percent of the market, up from five percent one year ago.

But some analysts believe that Synergy’s assertion of a “Big Four” in the cloud is a bit of a misnomer, considering the sheer size of AWS, which has established a lead so great that its market share is larger than that of Microsoft, IBM and Google combined.

Wikibon Senior Analyst Stuart Miniman

“Amazon is the clear leader,” said Wikibon analyst Stu Miniman (pictured right). “If we only look at the IaaS+PaaS space, AWS is well ahead of everyone else and has a growth rate that keeps pace with other challengers in the marketplace.”

But Amazon’s real lead could be even bigger than Synergy’s figures suggest. In her analysis on Seeking Alpha, Dana Blankenhorn postulates that Amazon’s true revenues may have been understated in Synergy’s research, noting that many startups are renting out AWS’ infrastructure and building their own services atop it.

“That’s because, as Synergy notes, cloud is, financially, built out of layers,” Blankenhorn writes. “Infrastructure is the base layer, just as operating systems were the base layer in previous eras. If you control the base layer, you allow your customers to gain market share in platforms or software, in service or applications, simply by piggybacking on your infrastructure.”

Despite Blankenhorn’s assertions, it’s still difficult to believe that Amazon will truly dominate cloud in the same way that proprietary software vendors have done in the past. When Microsoft ruled the operating systems market in the 1990s and early 2000s for example, there was no real, viable competition. But Wikibon’s Miniman suggested the Redmond firm’s cloud business could one day pose a much stronger challenge to AWS thanks to its strong enterprise ties.

“Microsoft is the clear number two today,” Miniman said. “Microsoft has a lot of enterprise applications and is doing a formidable job of helping customers transition to Office 365. It has the best story and adoption of that mix of pubic and on-premises for a single vendor hybrid cloud.”

Niche opportunity remains

Irrespective of whether its a “Big Four” or a “Big One plus Three,” Dinsdale said there’s still plenty of room for smaller players to carve out a niche for themselves due to the market’s rapid expansion.

“Developing the necessary global hyperscale data center infrastructure along with the required marketing and operations support is simply beyond the reach of all but a very small number of players,” Dinsdale said.

“This is not going to change, but the good news for the plethora of small-to-medium-sized cloud providers is that there does remain a wealth of opportunity for those that are focused on specific market niches or local geographic areas.”