US public IT cloud services revenue will experience a compound annual growth rate (CAGR) of 18.5% during 2011-2016, from $18.5 billion in 2011 to $43.2 billion in 2016, according to a new report by International Data Corporation (IDC): US Public IT Cloud Service by Industry Sector.

The new report focuses specifically on the public cloud services that are shared among unrelated enterprises and consumers, open to a largely unrestricted universe of potential users, and designed for a market, not a single enterprise. The forecast is segmented by five functional technology categories and by six vertical sectors.

"According to our research, the three verticals that accounted for more than 50% of the spending in 2011 are discrete manufacturing, professional services, and process manufacturing. This is not surprising as these industries are typically less risk averse and compliance focused," said Eileen Smith, program manager in IDC's Global Technology and Industry Research Organization. "Communications and media, education, and construction were found to be the fastest growing verticals. We expect the media portion of the communications and media vertical to continue to be one of the main users of storage on demand to enable continuous service for content-heavy customer offerings."

Additional key findings from the report include:

- Services and distribution, the largest sector, accounted for 30.3% of total revenue in 2011. Professional services alone accounted for nearly 40% of the entire category in 2011.

- Manufacturing and resources, the second-largest vertical sector, accounted for 24.0% of total public IT cloud services in 2011. Discrete manufacturing alone accounted for 46.7% of the entire category in 2011.

- Infrastructure, the fastest-growing sector with a 19.6% five-year CAGR, accounted for 12.3% of spending in 2011 and will account for 12.9% of spending by 2016.

The five functional primary market cloud services segments specifically forecasted in this pivot table are:

- Applications as a service

- System infrastructure software as a service (SaaS)

- Platform as a service (PaaS)

- Server as a service

- Basic storage as a service