The Online Ad World Is Murky. A Group of Companies Wants to Fix That.

“This is just one effort, but it is trying to address the larger issue of whether the digital advertising business will be more like the open internet, open to many, or will it be dominated by a few walled gardens?” said Randall Rothenberg, chief executive of the Interactive Advertising Bureau, which is aware of the initiative but is not directly involved. Nearly all the Source participants, as well as Google and Facebook, are members of the trade group.

“We’re trying to crack open the black box and compete on a different playing field than the walled gardens,” said Mark Zagorski, chief executive of Telaria, a company whose software is used by digital TV services like Hulu and Sling to maximize ad revenue.

The members of the initiative are making commitments to share data. Publishers and video distributors, for example, will have to verify the type of content they are supplying to meet quality and authenticity standards to guard against fraud. And ad tech companies will have to disclose their fees.

Moving to more open digital ad markets, giving buyers and sellers ample information on pricing and auctions, will take time, said Chris Guenther, a senior vice president at News Corporation, which owns The Wall Street Journal and The New York Post.

“But this initiative is a step in the right direction — toward transparency,” Mr. Guenther said.

Even without Google and Facebook, the companies say, the effort could help open up the digital ad business because it is in step with market demand.

“Buyers and sellers are looking to take more control of their business,” said Adam Soroca, an executive at the Rubicon Project, which provides tools to buyers and sellers of digital ads.

MediaMath has held discussions with Google about possibly joining the initiative, but not Facebook, the company said.