Brian Wieser, the oft-quoted former Pivotal Research analyst who became global president of business intelligence for WPP’s GroupM in 2019, is launching a media and advertising consultancy for investors, private equity firms and other industry players.

Wieser is launching the consultancy Madison and Wall, a name that plays on the figurative intersection of Madison Avenue and Wall Street. The new consultancy will have a Substack for those used to following his newsletters from GroupM or before that research notes from Pivotal.

His last day at GroupM was Jan. 28. Wieser said he will likely also consult for Pivotal.

At GroupM, Wieser will be succeeded by Kate Scott-Dawkins, who worked on his team, as lead forecaster, he said.

“There’s always a need to refine strategies and refine opportunities,” Wieser said. He characterized his approach as “rigorously scrutinizing the assumptions that businesses are making when they’re investing against opportunities.”

Wieser’s move comes amid a major shift over the past year, with digital media growth slowing, particularly among the behemoth players Google and Meta, and growth accelerating for connected TV and retail media. All that plays into major shifts in what the opportunities are, how they should be approached and who will be pursuing them.

“If you’re a large company going from 30% growth to 20% growth to 10% growth, it’s going to be really hard to get back to 30%,” Wieser said. That’s already resulted in big digital and ad tech players shifting from pure growth players to more of a focus on profitability—and related layoffs.

Related: Tracking layoffs and other economic moves

“For many sellers of advertising, the biggest opportunities are going to be to focus on your existing business and optimize it,” Wieser said. “And if you find a new billion-dollar revenue stream, great. It’s going to be hard for one company to find $10 billion revenue streams. But there are multiple billion-dollar revenue opportunities for smaller companies.”

CTV represents one big growth opportunity, but Wieser questions the extent to which that’s siphoning off growth of digital spending. He believes most is still a shift from linear TV.

Retail media growth requires similar assumption checking, Wieser said. Some of the growth has come from other digital media, he said. But some of it comes from packaged-goods trade or shopper spending.

And much of it, particularly for Amazon, has come from outside conventional U.S. advertisers, specifically third-party marketplace sellers, predominantly from China. That's a market Walmart Connect is trying to go after harder with the launch of its improved self-service ad tools last year.

Growth of CTV and retail media present some new challenges, particularly for big players, because it’s not clear that anyone will be able to consolidate the market or the supply chain to the extent Google has as the middle player in digital media or Meta in social media.

“Retail itself is so fragmented,” Wieser said. “Amazon has a huge share online, but certainly the rest of retail is very fragmented.” And while outside players such as Criteo and Publicis Groupe’s CitrusAD roll up a relatively small share of the market, it’s unclear that the biggest players will ever provide openings in their walled gardens to accommodate a common marketplace, he said.

Also see: Retail media networks attract ‘reluctant buyers’

Another big question with retail media is how much of the market ultimately will come from “non-endemic” advertisers, he said, who aren’t selling goods or services directly through the retailers whose media they buy. While that’s been a growing selling and talking point for retail media players, Wieser said it’s unclear how much of the whole such non-endemic advertisers represent.