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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5 Houston-area companies named among world's most innovative for 2026

In The Spotlight

Led by Conroe-based Hertha Metals, five organizations in the Houston area earned praise on Fast Company’s list of the World’s Most Innovative Companies of 2026.

Hertha Metals ranked No. 1 in the manufacturing category.

Last year, Hertha unveiled a single-step process for steelmaking that it says is cheaper, more energy-efficient and just as scalable as traditional steel manufacturing. It started testing the process in 2024 at a one-metric-ton-per-day pilot plant.

At the same time, Hertha announced more than $17 million in venture capital funding from investors such as Breakthrough Energy, Clean Energy Ventures, Khosla Ventures, and Pear VC.

“We’re not just reinventing steelmaking; we’re redefining what’s possible in materials, manufacturing, and national resilience,” Laureen Meroueh, founder and CEO of Hertha, said at the time.

Meroueh was also recently named to Inc. Magazine's 2026 Female Founders 500 list.

Hertha, founded in 2022, says traditional steelmaking relies on an outdated, coal-based multistep process that is costly, and contributes up to 9 percent of industrial energy use and 10 percent of global carbon emissions.

By contrast, Hertha’s method converts low-grade iron ore into molten steel or high-purity iron in one step. The company says its process is 30 percent more energy-efficient than traditional steelmaking and costs less than producing steel in China.

Last year, Hertha said it planned to break ground in 2026 on a plant capable of producing more than 9,000 metric tons of steel per year. In its next phase, the company plans to operate at 500,000 metric tons of steel production per year.

Here are Fast Company’s rankings for the four other Houston-area organizations:

  • Houston-based Vaulted Deep, No. 3 in catchall “other” category.
  • XGS Energy, No. 7 in the energy category. XGS’ proprietary solid-state geothermal system uses thermally conductive materials to deliver affordable energy anywhere hot rock is located. While Fast Company lists Houston as XGS’ headquarters, and the company has a major presence in the city, XGS is based in Palo Alto, California.
  • Houston-based residential real estate brokerage Epique Realty, No. 10 in the business services category. Epique, which bills itself as the industry’s first AI brokerage, provides a free AI toolkit for real estate agents to enhance marketing, streamline content creation, and improve engagement with clients and prospects.
  • Texas A&M University’s Nanostructured Materials Lab in College Station. The lab studies nano-structured materials to make materials lighter for the aerospace industry, improve energy storage, and enable the creation of “smart” textiles.
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This article first appeared on our sister site, EnergyCapitalHTX.com.

UH lands $11.8M for first-of-its-kind early language development study

speech funding

Researchers at the University of Houston have secured an $11.8 million grant from the National Institutes of Health to conduct a first-of-its-kind study of early language development.

Led by Elena Grigorenko, the Hugh Roy and Lillie Cranz Cullen Distinguished Professor of Psychology, and research professor Jack Fletcher, the study will follow 3,600 children aged 18 to 24 months to uncover how language skills develop at this critical stage and why some children experience delays that can influence later growth.

The NIH funding will also support the development of the new national Clinical Research Center on Developmental Language Disorders at UH, which aims to bring experts from psychology, education, health and measurement sciences to study how children learn language.

“This will be the first national study to estimate how common late talking is using a large, representative sample of Houston toddlers,” Grigorenko said in a news release. “By following these children as they grow, we hope to better understand the developmental pathways that can lead to conditions such as developmental language disorder and autism.”

UH’s team will partner with the pediatric clinic network at Texas Children’s Hospital, where children will be screened for early language development, allowing researchers to identify those who show signs of delayed speech. Next, researchers will follow the cohort through early childhood to examine how language abilities evolve and how early delays may lead to later challenges.

The Clinical Research Center on Developmental Language Disorders will be the 14th national research center established at UH, and will include researchers from multiple UH departments, as well as partners at Baylor College of Medicine and the Texas Center for Learning Disorders.

“This level of investment from the National Institutes of Health reflects the significance of this work to address a complex challenge affecting children, families and communities,” Claudia Neuhauser, vice president for research at UH, said in a news release. “By bringing together experts from multiple disciplines and partnering with major health systems across the region, the project reflects our commitment to advancing discoveries that impact our community.”

Rice Alliance names Houston healthtech exec as first head of platform

new hire

The Rice Alliance for Technology and Entrepreneurship has named its first head of platform.

Houston entrepreneur Laura Neder stepped into the newly created role last month, according to an email from Rice Alliance. Neder will focus on building and growing Houston’s Venture Advantage Platform.

The emerging platform, which is being promoted by Rice Alliance and the Ion, aims to connect founders with the "people, capital and expertise they need to scale."

"I’ve spent a lot of time thinking about what it takes to make an innovation ecosystem more navigable, more connected, and more useful for founders," Neder said in a LinkedIn post. "I’m grateful for the opportunity to do that work at Rice Alliance, alongside a team with a long history of supporting entrepreneurship and innovation."

"Houston has the talent, institutions, and industry base to create real advantage for founders," she added. "I’m looking forward to listening, learning, and building stronger pathways across the ecosystem."

Neder most recently served as CEO of Houston-based Careset, where she helped bring the Medicare data startup to commercialization. Prior to that, Neder served as COO of Houston-based telemedicine startup 2nd.MD, which was acquired for $460 million by Accolade in 2021.

"Laura brings a rare combination of founder empathy, operational experience and ecosystem leadership," Rice Alliance shared.

Neder and Rice Alliance also shared that the organization is hiring developers to design the new Venture Advantage Platform. Learn more here.

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