AMENIA, NY – The long-standing boundaries between buying and selling in programmatic advertising are dissolving as supply-side platforms assert greater influence over media investment decisions.
“The supply side is taking on an increasingly more significant role in media buying today,” Gregory Sherrill, VP of Demand at Magnite, told Beet.TV contributor David Kaplan in an interview at the Beet Retreat Berkshires 2025. This shift reflects a fundamental evolution in how programmatic dollars flow through the advertising ecosystem, driven by the explosive growth of connected TV and the industry’s hunger for transparency.
From Sherrill’s perspective, the transformation fits with Magnite’s ability to bridge programmatic and direct buying through its SpringServe video ad serving platform. The company unveiled SpringServe in April 2025 with clients such as Disney Advertising, LG Ad Solutions, Paramount, Roku, Samsung, and Warner Bros. Discovery taking advantage of it.
“That is exactly how we bring publisher side technology to the buy side and how publisher side technology can fill a lot of the space between how people buy programmatically and how they buy via direct,” Sherrill explained.
The transparency imperative
Behind this supply-side evolution lies an urgent industry demand for clarity around where programmatic dollars actually go. With billions flowing into automated buying, questions about technology layers and value extraction have reached a critical mass.
“There are so many dollars being invested into programmatic that there needs to be a lot of questions asked: ‘What are the technology layers from the buy side? From the publisher side? From technology sides and everything in between,’” Sherrill said. “What is the value that they’re extracting versus the value that they’re bringing to all of those parties?”
The company’s approach merges its SpringServe video platform with Magnite Streaming to provide deeper visibility into the supply chain, particularly for connected TV campaigns.
The challenge, Sherrill noted, isn’t making transparency available but ensuring downstream systems can process and act on that information.
“The questions really start to come down to not what we can make available, but what either DSPs are able to read and recognize on their side,” he said. This technical limitation often determines whether transparency data gets used for real-time campaign optimization or relegated to post-campaign analysis.
Breaking down attribution silos
The supply-side platform’s strategic role extends beyond transparency into solving one of advertising’s most persistent challenges: cross-channel attribution. Traditional buying approaches trap advertisers in format-specific silos, limiting their ability to understand true campaign impact.
“So much is bought in silos and you see video investment teams focus on the marquee big publishers, which is great,” Sherrill observed. But in an omnichannel world, this fragmented approach undermines measurement accuracy and optimization opportunities.
Magnite’s solution involves partnering with third-party measurement companies and agencies’ proprietary data solutions to create integrated attribution models. “It’s complicated, but I think ways to make it easy so that people from all the way from the brand of the agency and down through to the publisher can see it,” Sherrill said.
The direct-programmatic convergence
Magnite’s overarching goal is to collapse the traditional distinction between direct and programmatic buying through SpringServe video platform and buyer marketplace. This hybrid approach allows buyers to access inventory through direct insertion orders, DSP capabilities, and guaranteed programmatic buying within a single interface.
“It combines ways that they work in a direct IO capacity within the publisher ad server, it combines DSP capabilities and it provides clear line buy capabilities,” Sherrill said. This convergence represents a fundamental shift in how media transactions occur, offering buyers maximum flexibility while maintaining publisher control.
The model also addresses fee transparency concerns by clearly delineating what Magnite extracts from each transaction.
“There’s a lot of value in that,” Sherrill said. “It really starts to bring value also to the buy side and helps to simplify the process.”
