New York-based advertising technology firm AppNexus, Inc. has acquired rival Yieldex, Inc. in a move speculated to be leading to an Initial Public Offering (IPO).

Officially, the price of the acquisition was not disclosed; however, The Wall Street Journal puts the figure at $100 million in a mixture of cash and stock.

Claimed to be the largest independent advertising technology services provider, AppNexus offers trading solutions and powers advertising marketplaces with an open, unified and powerful programmatic platform that it says empowers customers to more effectively buy and sell media, allowing them to innovate, differentiate and transform their businesses.

Yieldex offers a similar yet complementary platform via Yieldex Analytics, a forecasting and analytics tool that enables publishers to increase revenue and yield, and YieldexDirect, an integrated catalog management and direct booking capability for direct guaranteed buys.

One of the strongest parts of the Yieldex buy will be its client book, with the platform powering direct sales for over 50 major publishers, including The New York Times Co., Expedia, Inc., Pandora Media, Inc., CBS Interactive, Univision and The Weather Channel, LLC.

“We’re building a best-in-class, full-stack publisher platform, and the integration of Yieldex’s sophisticated analytics and forecasting tools helps us solve unmet challenges and deliver key insights to our clients,” CEO of AppNexus Brian O’Kelley said in a statement. “This deal also positions us to lead on programmatic direct – one of the next big waves in advertising technology. The marriage of the AppNexus platform and Yieldex creates a comprehensive, open marketplace for programmatic direct.”

Yieldex was founded in 2007 and had raised $18.5 million over three rounds prior to acquisition, from investors including First Round, Amazon, Madrona Venture Group, Sequel Venture Partners, Triangle Peak Partners, LP, Hearst Ventures and Woodside Fund.

AppNexus is definitely the larger of the two companies, having raised $310.5 million over seven rounds from investors, including Venrock, Microsoft, First Round and others. The company is reported to have a valuation of $1.2 billion.

Yieldex is AppNexus’ third acquisition, having previously acquired ad companies MediaGlu, Inc. and ALENTY, Inc. in 2014.

Market consolidation and an IPO exit

There’s not a lot of really big, independent advertising technology firms out in the marketplace in 2015, and this acquisition just made AppNexus somewhat bigger again.

According to reports, the company had previously considered an IPO, but with this purchase it may be back into consideration for the second half of the year.

The problem with these sorts of firms is there’s only so many giants, such as Google around that can acquire them, and the likes of the Mountain View search giant, along with competitors such as Microsoft, Yahoo! Inc. and others already have their own advertising tech platforms; the comparison might be somewhat apples versus oranges as AppNexus more offers a SaaS platform complete with open API to power other sites, but there is some cross-over.

An IPO might be the logical way for the company to keep growing, particularly given a number of its investors would be looking for opportunities for an exit after having been in the company for anything up to 8 years.