Wireless infrastructure provider American Tower Corp., which has a $35 billion enterprise value, converted to a REIT earlier this year. Other tower companies and data center operators are considering the move, and billboard advertising companies could also make the transition to REIT-hood. The premium that these tax-light structures attain could influence the way that private equity thinks about leveraged buyout valuations.

Wireless tower and data center REITs are not exactly new. Though these companies serve telecoms and large corporate clients, the businesses have real estate components. A tower is an apartment building for wireless transmitters. A data center is a parking garage for servers.

"The reason that towers and data centers in particular are interesting as REITs right now is that they have REIT characteristics, but they have fundamental growth drivers that are significantly more robust than the growth drivers for traditional real estate," Evercore Partners Inc. analyst Jonathan Schildkraut said. "Hotels are not growing the way data centers are."

Some examples in the tower sector include Macquarie Group-backed private REIT Global Tower Partners and the former Global Signal Inc., which was a public REIT before its acquisition by Crown Castle International Corp.

"Tower companies have said for years now that they plan to convert to REITs once they used up their NOLs," noted Clayton Moran of Benchmark Co. LLC.

A number of the large tower companies are contemplating the expiration of net operating losses that allow them to shield their income from taxes. This reality was the governing factor in the timing of American Tower's conversion. And Crown Castle has suggested that it would consider REIT conversion around 2016.

SBA Communications Inc. said during a February investor conference that it still has about $1.2 billion in federal NOLs. Chief executive Jeff Stoops estimated that the tax benefits would carry the company, "six, seven, eight years out, depending on future portfolio growth."

About 90% of the $518 billion REIT equity capital is devoted to traditional real estate such as offices and housing and to niches including assisted living, hotels and storage, Wells Fargo Securities LLC said in an August report. But specialty REITs including data centers, towers and laboratory space are emerging. Wells Fargo launched joint coverage of American Tower in August, with analysts from its telecom and REIT teams.

The investments carry more risk because, among other reasons, a company can't repurpose a wireless tower as easily as an office supply shop.

"However, the scarcity of these products allows owners to command significant rent premiums as compared [to] their closest commercial real estate peer," Wells Fargo analyst Jennifer Fritzsche wrote in the report announcing coverage of American Tower.

There are a number of data center REITs, including Digital Realty Trust Inc., DuPont Fabros Technology Inc. and CoreSite Realty Corp.

Data center operator Equinix Inc., with an enterprise value around $11 billion, has said that it is considering a conversion. Cincinnati Bell Inc. announced this summer that it intends to spin off CyrusOne, its data center unit, as a REIT, though it is waiting for a tax ruling. Cincinnati Bell bought CyrusOne from Abry Partners LLC for $525 million in 2010.

It would be challenging for a startup data center to become a REIT, Moran said, because the companies need their capital to develop the business. "As they mature," he noted, "they can handle both investment and payment of a dividend."

Moran added that data center REITs have enjoyed a premium that likely contributed to Equinix's interest in converting. The disparity between data center REITs and non-REITs has become clouded as the markets price tax benefits into the stocks. Equinix has neared Moran's estimate for the REITs, of about 14 times estimated 2012 Ebitda.

Evercore's Schildkraut values the data center REITs at about 15.3 times 2012 Ebitda, and the non-REITs at a multiple of 13.

The REIT premium may also creep into M&A valuations. Schildkraut wrote in a July note that the potential for a REIT offering supported the valuation in GI Partners LLP's $720 million sale of Telx Group Inc. to Berkshire Partners LLC and Abry Partners.

The analyst put the valuation at 19 times Ebitda. At the time, his report noted, Equinix traded at 9 times Ebitda.

A data center operator could also achieve a higher valuation multiple by getting into cloud computing. For example, Internap Network Services Corp. has used M&A to expand its cloud offerings.

"It's a more complicated change than declaring yourself a REIT," Moran said of entering the cloud business. "It's certainly possible and can make sense for some companies, but it differs from their core competency and would be a change in strategy."

Developments may allow advertisers to become REITs.

Lamar Advertising Co. said during an August investor call that it is considering a conversion after a recent Internal Revenue Service ruling about the status of billboards as real property. Sean Reilly, CEO of Lamar, said during the call, "There's no other advertising-based entity that has a REIT structure."

Evercore analyst Doug Arthur suggested in a recent report that, as a REIT, Lamar could be valued in the high $30 range. Absent a conversion, he would target the stock at $26 per share.

It goes without saying that the ability to shield income from taxes would increase a stock's value. However, the REIT premium may diminish depending on interest rates.

"Historically, REIT valuations broadly are inversely tied to interest rates," Evercore's Schildkraut explained. "In a higher interest rate environment, the disparity between REITs and non-REITs may not be as great."