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.


Ad Placement 300x100
Ad Placement 300x600

CultureMap Emails are Awesome

Property Showcase

Houston's Ion District to expand with new research and tech space, The Arc

coming soon

Houston's Ion District is set to expand with the addition of a nearly 200,000-square-foot research and technology facility, The Arc at the Ion District.

Rice Real Estate Company and Lincoln Property Company are expected to break ground on the state-of-the-art facility in Q2 2026 with a completion target set for Q1 2028, according to a news release.

Rice University, the new facility's lead tenant, will occupy almost 30,000 square feet of office and lab space in The Arc, which will share a plaza with the Ion and is intended to "extend the district’s success as a hub for innovative ideas and collaboration." Rice research at The Arc will focus on energy, artificial intelligence, data science, robotics and computational engineering, according to the release.

“The Arc will offer Rice the opportunity to deepen its commitment to fostering world-changing innovation by bringing our leading minds and breakthrough discoveries into direct engagement with Houston’s thriving entrepreneurial ecosystem,” Rice President Reginald DesRoches said in the release. “Working side by side with industry experts and actual end users at the Ion District uniquely positions our faculty and students to form partnerships and collaborations that might not be possible elsewhere.”

Developers of the project are targeting LEED Gold certification by incorporating smart building automation and energy-saving features into The Arc's design. Tenants will have the opportunity to lease flexible floor plans ranging from 28,000 to 31,000 square feet with 15-foot-high ceilings. The property will also feature a gym, an amenity lounge, conference and meeting spaces, outdoor plazas, underground parking and on-site retail and dining.

Preleasing has begun for organizations interested in joining Rice in the building.

“The Arc at the Ion District will be more than a building—it will be a catalyst for the partnerships, innovations and discoveries that will define Houston’s future in science and technology,” Ken Jett, president of Rice Real Estate Company, added in the release. “By expanding our urban innovation ecosystem, The Arc will attract leading organizations and talent to Houston, further strengthening our city’s position as a hub for scientific and entrepreneurial progress.”

Intel Corp. and Rice University sign research access agreement

innovation access

Rice University’s Office of Technology Transfer has signed a subscription agreement with California-based Intel Corp., giving the global company access to Rice’s research portfolio and the opportunity to license select patented innovations.

“By partnering with Intel, we are creating opportunities for our research to make a tangible impact in the technology sector,” Patricia Stepp, assistant vice president for technology transfer, said in a news release.

Intel will pay Rice an annual subscription fee to secure the option to evaluate specified Rice-patented technologies, according to the agreement. If Intel chooses to exercise its option rights, it can obtain a license for each selected technology at a fee.

Rice has been a hub for innovation and technology with initiatives like the Rice Biotech Launch Pad, an accelerator focused on expediting the translation of the university’s health and medical technology; RBL LLC, a biotech venture studio in the Texas Medical Center’s Helix Park dedicated to commercializing lifesaving medical technologies from the Launch Pad; and Rice Nexus, an AI-focused "innovation factory" at the Ion.

The university has also inked partnerships with other tech giants in recent months. Rice's OpenStax, a provider of affordable instructional technologies and one of the world’s largest publishers of open educational resources, partnered with Microsoft this summer. Google Public Sector has also teamed up with Rice to launch the Rice AI Venture Accelerator, or RAVA.

“This agreement exemplifies Rice University’s dedication to fostering innovation and accelerating the commercialization of groundbreaking research,” Stepp added in the news release.

Houston team develops low-cost device to treat infants with life-threatening birth defect

infant innovation

A team of engineers and pediatric surgeons led by Rice University’s Rice360 Institute for Global Health Technologies has developed a cost-effective treatment for infants born with gastroschisis, a congenital condition in which intestines and other organs are developed outside of the body.

The condition can be life-threatening in economically disadvantaged regions without access to equipment.

The Rice-developed device, known as SimpleSilo, is “simple, low-cost and locally manufacturable,” according to the university. It consists of a saline bag, oxygen tubing and a commercially available heat sealer, while mimicking the function of commercial silo bags, which are used in high-income countries to protect exposed organs and gently return them into the abdominal cavity gradually.

Generally, a single-use bag can cost between $200 and $300. The alternatives that exist lack structure and require surgical sewing. This is where the SimpleSilo comes in.

“We focused on keeping the design as simple and functional as possible, while still being affordable,” Vanshika Jhonsa said in a news release. “Our hope is that health care providers around the world can adapt the SimpleSilo to their local supplies and specific needs.”

The study was published in the Journal of Pediatric Surgery, and Jhonsa, its first author, also won the 2023 American Pediatric Surgical Association Innovation Award for the project. She is a recent Rice alumna and is currently a medical student at UTHealth Houston.

Bindi Naik-Mathuria, a pediatric surgeon at UTMB Health, served as the corresponding author of the study. Rice undergraduates Shreya Jindal and Shriya Shah, along with Mary Seifu Tirfie, a current Rice360 Global Health Fellow, also worked on the project.

In laboratory tests, the device demonstrated a fluid leakage rate of just 0.02 milliliters per hour, which is comparable to commercial silo bags, and it withstood repeated disinfection while maintaining its structure. In a simulated in vitro test using cow intestines and a mock abdominal wall, SimpleSilo achieved a 50 percent reduction of the intestines into the simulated cavity over three days, also matching the performance of commercial silo bags. The team plans to conduct a formal clinical trial in East Africa.

“Gastroschisis has one of the biggest survival gaps from high-resource settings to low-resource settings, but it doesn’t have to be this way,” Meaghan Bond, lecturer and senior design engineer at Rice360, added in the news release. “We believe the SimpleSilo can help close the survival gap by making treatment accessible and affordable, even in resource-limited settings.”
View All Listings