Houston founder shares how he's using tech to make digital media more effective and equitable

houston innovators podcast episode 173

This month, Mark Walker is celebrating his company's one year anniversary of going public — only the ninth Black-founded business to accomplish this feat on a U.S. stock exchange. Photo courtesy

After working in both sides of the advertising world, Mark Walker thought he could reimagine a platform that would be more efficient and equitable.

Walker co-founded his company, Direct Digital Holdings, an adtech platform, after serving in several roles — from an early hire at Houston digital media startup Questia to business development director at NRG Energy and COO of EBONY Media. He shares on the Houston Innovators Platform how he took this experience in tech, advertising, and media to create his company's platform.

"NRG Energy gave me a top-down view of the value chain, and Ebony gave me a bottoms-up view of the value chain of how media is purchased," Walker says on the show. "At Direct Digital Holdings, we help companies buy and sell media — and we leverage technology to do it. It's really the culmination of both of those experiences."

With over 30,000 publishers on its platform, Direct Digital makes it easier for its core customers — middle market companies looking to buy into the digital media ecosystem — to tap into these opportunities without the tech know-how they might otherwise need. Walker explains that at EBONY, he saw how small to midsize publications — especially the multicultural ones — were being left out on the ad selling side of the equation. The Direct Digital platform bridges the gap on each end.

Founded in 2018 in partnership with Keith Smith, who went through similar professional experiences, Direct Digital went public exactly one year ago after growing the company through strategic M&A activity. Walker says the decision to IPO made the most sense for his company — though it wasn't an easy process. Direct Digital is only the ninth company founded by a Black entrepreneur to go public on a US stock exchange.

"If you think the process is hard — it actually is," Walker says on the journey to IPO. "We were a privately held company, and we knew we had a good growth trajectory and we looked a couple different options. We decided to go public in a very traditional way."

Walker explains there were some risks involved, but the co-founders ultimately decided to shy away from adding in investors who might not have the same ideas for the company's future.

Direct Digital has been a Houston company from the star — despite the city not being home to a booming adtech ecosystem. Instead, Houston — with its collection of Fortune 500 companies and rich diversity — has allowed the business to stand out.

"If you look at and reflect on how our company has been built — from our board of directors to our leadership and management team — we're a majority minority organization all the way across the board," Walker says. "Diversity is very important to us. It's the lifeblood of our business — especially because we're serving publishers in those communities in big way. And moreso, we think you get the best product, thoughts, and ideas from a diverse workforce, and Houston fits right into that mold for us."

Walker shares more about his company's future, advice on IPO, and what all he's watching in adtech — from AI to streaming — on the podcast. Listen to the interview below — or wherever you stream your podcasts — and subscribe for weekly episodes.


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Screen-free hiking app developed in Houston earns 'Best of the Best' award

Peak Prize

An AI-powered, screen-free hiking system developed by Varshini Chouthri, a recent industrial design graduate from the University of Houston, has received Red Dot’s “Best of the Best” award, which recognizes the top innovative designs around the world.

Known as NOMAD, the system aims to help users stay in the moment while still utilizing technology. It will go on to compete for the Red Dot Luminary Award, the highest recognition given at the international event.

“NOMAD was truly a passion project, inspired by years of hiking growing up, where the outdoors became a place of peace, challenge, and reflection,” Chouthri said in a news release.

“I wanted to design something supporting those kinds of experiences by helping hikers feel more grounded and confident while staying present in nature. It was a way to give back to the moments that made me fall in love with the outdoors in the first place.”

The app “reimagines” outdoor exploration by removing the dependence on screens by using adaptive AI, contextual sensing, and an optional, wearable companion device. It employs a circular learning model that enables hikers to receive real-time guidance, safety alerts, personalized trip planning, hands-free navigation and more through a natural interface, according to UH.

NOMAD was developed at the Hines College of Architecture and Design’s PXD LAB. In 2023, Lunet, developed by David Edquilang at Hines College, received the “Best of the Best” recognition and went on to win the Red Dot Luminary Award.

The PXD LAB offers a platform to expand concepts into system-level designs that address real-world challenges, according to UH.

“Varshini’s work on NOMAD exemplifies the future-focused, systems-driven thinking we promote in the Advanced UX Design curriculum,” Min Kang, director of PXD LAB, added in the release. “NOMAD goes beyond being just a product; it reimagines how technology can enhance outdoor exploration without disrupting the experience.”

In addition to the Red Dot honors, NOMAD has already earned distinction from the FIT Sport Design Awards and was a finalist for the International Design Excellence Awards (IDEA) presented by the Industrial Designers Society of America.

NASA signs on latest tenant for new Exploration Park campus, now underway

space hub

Exploration Park, the 240-acre research and commercial institute at NASA's Johnson Space Center, is ready for launch.

Facilities at the property have broken ground, according to a recent episode of NASA's Houston We Have a Podcast, with a completion date targeted for Q4 2026.

The research park has also added Houston-based KBR to its list of tenants. According to a news release from the Greater Houston Partnership, the human spaceflight and aerospace services company will operate a 45,000-square-foot food innovation lab at Exploration Park. KBR will use the facility to focus on customized food systems, packaging and nutrition for the low Earth orbit economy.

“Exploration Park is designed for companies in the space ecosystem, such as KBR, to develop, produce, and deploy innovative new technologies that support space exploration and commerce,” Simon Shewmaker, head of development at ACMI Properties, the developer behind Exploration Park, said in the GHP release. “This project is moving expeditiously, and we’re thrilled to sign such an innovative partner in KBR, reflecting our shared commitment to building the essential infrastructure of tomorrow for the next generation of space innovators and explorers.”

NASA introduced the concept of a collaborative hub for academic, commercial and international partners focused on spaceflight in 2023. It signed leases with the American Center for Manufacturing and Innovation and the Texas A&M University System for the previously unused space at JSC last year.

“For more than 60 years, NASA Johnson has been the hub of human space exploration,” Vanessa Wyche, NASA Johnson Space Center Director, said in a statement at the time. “This Space Systems Campus will be a significant component within our objectives for a robust and durable space economy that will benefit not only the nation’s efforts to explore the Moon, Mars and the asteroids, but all of humanity as the benefits of space exploration research roll home to Earth.”

Texas A&M is developing the $200 million Texas A&M Space Institute, funded by the Texas Space Commission, at the center of the park. The facility broke ground last year and will focus on academic, government and commercial collaboration, as well as workforce training programs. ACMI is developing the facilities at Exploration Park.

Once completed, Exploration Park is expected to feature at least 20 build-to-suit facilities over at least 1.5 million square feet. It will offer research and development space, laboratories, clean rooms, office space and light manufacturing capabilities for the aerospace, robotics, life support systems, advanced manufacturing and artificial intelligence industries.

According to the GHP, Griffin Partners has also been selected to serve as the co-developer of Exploration Park. Gensler is leading the design and Walter P Moore is overseeing civil engineering.

Houston cleantech co. plans first-of-its-kind sustainable aviation fuel facility

coming soon

Houston-based Syzygy Plasmonics announced plans to develop what it calls the world's first electrified facility to convert biogas into sustainable aviation fuel (SAF).

The facility, known as NovaSAF 1, will be located in Durazno, Uruguay. It is expected to produce over 350,000 gallons of SAF annually, which would be considered “a breakthrough in cost-effective, scalable clean fuel,” according to the company.

"This is more than just a SAF plant; it's a new model for biogas economics," Trevor Best, CEO of Syzygy Plasmonics, said in a news release. "We're unlocking a global asset class of underutilized biogas sites and turning them into high-value clean fuel hubs without pipelines, costly gas separation, or subsidy dependence.”

The project is backed by long-term feedstock and site agreements with one of Uruguay's largest dairy and agri-energy operations, Estancias del Lago, while the permitting and equipment sourcing are ongoing alongside front-end engineering work led by Kent.

Syzygy says the project will result in a 50 percent higher SAF yield than conventional thermal biogas reforming pathways and will utilize both methane and CO2 naturally found in biogas as feedstocks, eliminating the need for expensive CO2 separation technologies and infrastructure. Additionally, the modular facility will be designed for easy replication in biogas-rich regions.

The new facility is expected to begin commercial operations in Q1 2027 and produce SAF with at least an 80 percent reduction in carbon intensity compared to Jet A fuel. The company says that once fully commercialized the facility will produce SAF at Jet-A fuel cost parity.

“We believe NovaSAF represents one of the few viable pathways to producing SAF at jet parity and successfully decarbonizing air travel,” Best added in the release.

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This article originally ran on EnergyCapital.

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