The hottest trend among hoteliers at the moment is the concept of “soft-branding” — that is, adding prominent hotels to a “collection,” rather than reflagging them with their own brands.

The hottest trend among hoteliers at the moment is the concept of “soft-branding” — that is, adding prominent hotels to a “collection,” rather than reflagging them with their own brands.

In recent months, the battle for soft-brand supremacy among the largest U.S. hotel companies has become increasingly aggressive.

For example, Hilton Worldwide announced last month that it had hooked the nearly completed 1,620-room SLS Las Vegas Hotel & Casino for its new Curio collection of hotels.

Marriott International upped the ante by announcing earlier this month that it had snared the 3,414-room Atlantis Paradise Island in the Bahamas.

The property, owned by Brookfield Asset Management and managed by Kerzner International, will join Marriott’s Autograph Collection under a franchise agreement in September.

In a July 2 statement, Marriott CEO Arne Sorenson, whose company will also back the 20-year-old Atlantis with a $100 million In a July 2 statement, Marriott CEO Arne Sorenson, whose company will also back the 20-year-old Atlantis with a $100 million mezzanine loan, called the deal a "milestone agreement." called the deal a “milestone agreement.”

Mark Eble, regional vice president for consultant PKF Hospitality, agreed.

Indeed, the agreement reflects how hoteliers, ranging from primarily upper-upscale operators like Starwood Hotels & Resorts to more midprice specialists like Choice Hotels International, are finding ways to boost both revenue and exposure without violating existing agreements with hotel owners not to open more of their own branded properties in established markets.

In all cases, soft-branding offers hotel owners hugely expanded reservations and marketing services, and in some cases, joining a collection also means that the hotel company takes over actual management responsibilities.

The Autograph Collection, which launched in 2010, includes such properties as Las Vegas’ Cosmopolitan and London’s St. Ermin’s Hotel. In all, the collection comprised 60 hotels as of March 31, up from 41 a year earlier, having added properties such as the Pier One Sydney Harbour and Berlin’s Steinplatz since the beginning of the year.

Meanwhile, Hilton last month said that in addition to the SLS Las Vegas, which is scheduled to open at the old Sahara site on Labor Day weekend, Houston’s 90-year-old Sam Houston Hotel and the Franklin Hotel in Chapel Hill, N.C., would join Curio.

In February, Carlson Rezidor announced a luxury soft brand called Quorvus and said in May that the Edinburgh and Kuwait properties formerly under the Hotel Missoni brand would join that group.

And Choice Hotels announced in January the addition of Chicago’s Hotel Blake as the 100th U.S. hotel to join its Ascend Collection of upscale independent hotels. It has since raised that total to 125.

Jan Freitag, senior vice president of strategic development at research firm STR, said that adding properties such as Atlantis and the SLS Las Vegas enables hoteliers to offer their most loyal guests a more valuable “earn and burn” proposition: Guests can use loyalty points earned on business trips for leisure trips.

More importantly, soft-branded hotels give hotel operators a chance to broaden their reach by including hotels in established markets that in many cases wouldn’t otherwise fit an existing brand profile.

“We had this brand proliferation in the 1990s and 2000s, and it’s very hard for brands to expand into big markets because they’re already there,” Freitag said. “The soft brands allow them to have another vehicle to get their name in front of the customer without hurting either the existing brands or existing contracts.”

Just where the soft-branding concept started is open to debate. While some analysts have said Hilton followed Marriott’s lead, Hilton has actually been practicing a less formal version of soft branding for decades with historical Chicago hotels such as the Palmer House and the Drake.

Meanwhile, Choice Hotels CEO Stephen Joyce, in a 2012 interview with Travel Weekly, pointed out that the Ascend Collection preceded the Autograph Collection by about two years.

Starwood Hotels’ global brand manager, Paul James, speaking at a hotel conference last month, pointedly noted that his company’s Luxury Collection had Hilton beat by about two decades. And Eble asserted that the real progenitors of soft branding were companies such as Leading Hotels of the World and Preferred Hotel Group, which have been around since 1928 and 1968, respectively.

Regardless, if the Autograph Collection’s performance is any indication, guests appear to be appreciating the combination of big-brand booking convenience and the escape from a cookie-cutter vibe that soft branding can offer.

Last year, Autograph Collection hotels in North America boosted their collective revenue per available room (RevPAR) by 8.8%, easily outpacing Marriott’s 5% RevPAR increase in North America. And for the first quarter, Autograph Collection hotels’ RevPAR spiked 13% from a year earlier, with room rates jumping 11%.

That kind of performance has attracted at least one major hotel investor looking to benefit from soft-branding efforts by both Hilton and Marriott, the two largest U.S. hotel companies.

In May, Blackstone Group, which has a majority stake in Hilton Worldwide, agreed to acquire the 2,995-room Cosmopolitan, which had been the Autograph Collection’s largest property prior to the Atlantis announcement, for $1.73 billion.

Eble said the attraction for investors is clear.

“It’s more about how these big hotel companies get more rooms into a market than serving some closely defined customer niche,” he said. “In markets that might be saturated with existing brands, both Marriott and Hilton are now coming in with the same story.”