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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Houston bio-based materials startup breaks into footwear

cleaner shoes

A more sustainable shoe can’t be built on a single material swap. From the hard plastics hidden inside a heel to the material covering a sneaker’s upper, footwear is a collection of components—and each presents a different challenge for companies trying to move away from conventional, petroleum-based materials.

Houston-based Rheom Materials wants to change that equation. The biomaterials company has launched a sustainable footwear platform featuring two of its bio-based alternatives: Benree, a biodegradable plastic designed for hard internal components, and ShoraiDura, a durable leather alternative for footwear uppers.

“A shoe is not one material; it is multiple parts working together as a system. Substituting a single material has never moved the needle,” Rheom founder and CEO Zimri Hinshaw said in a news release. “Rheom wants to make it easier for brands to make a positive impact. By providing an assortment of bio-based materials, brands can change the system, not just a swatch of it.”

Benree is Rheom’s alternative to conventional hard plastics used in footwear construction. The company says it is a 100 percent USDA-certified bio-based, biodegradable material with performance comparable to acrylonitrile butadiene styrene (ABS), a widely used engineering plastic.

The material has passed SATRA testing for high-heel applications with Bared Footwear, an Australian footwear brand.

“At Bared, we're constantly on a journey to remove plastic from our shoes. At the same time, our brand won't compromise on quality for the end customer,” Millie Richards, Bared’s head of sustainability, added in the release. “From samples and testing, Rheom has proven to be solving both of those problems for us. We look forward to seeing how they develop as a company and would love to use them in our shoes.”

Rheom says it is also exploring Benree for additional internal components, including toe puffs and heel counters.

Rheom's Benree material was used for a high-heel prototype. Photo courtesy Rheom Materials

The company’s ShoraiDura material addresses another major part of shoe construction: the upper, which must withstand repeated flexing, friction and wear while maintaining its appearance.

Containing about 80 percent bio-based content, ShoraiDura is engineered as a durable leather alternative for footwear. Rheom says the material’s molecular structure is designed to deliver the strength and durability required for demanding applications.

To demonstrate how the material could be used in finished products, Rheom worked with a Los Angeles-based footwear manufacturer to create two prototypes: an athletic sneaker and a textured skater shoe, both featuring ShoraiDura uppers.

The two offerings reflect the company’s broader strategy. Rather than asking brands to evaluate a single material in isolation, Rheom is positioning its platform as a way to explore alternatives across different parts of footwear construction.

The next step is broader industry adoption. Benree’s testing with Bared Footwear and ShoraiDura’s footwear prototypes offer early examples of how the materials could be applied, while commercial use will depend on manufacturers’ evaluations and product-development decisions.

Rheom Materials is a Houston-based biomaterials company developing bio-based alternatives to petrochemical plastics. Its product portfolio includes Shorai, a leather alternative, and Benree, a hard plastic alternative.

The company debuted Shorai at the Houston Livestock Show and Rodeo in 2025 and showed a bio-based "leather" collection in Milan earlier this year. Read more here.

Houston's Rice University named the No. 1 best Texas college for 2027

We're No. 1

With early application season in full swing, a local university is racking up accolades on a new list of the 10 best Texas colleges for 2027.

Rice University topped the list as the No. 1 best university in Texas in WalletHub's annual "College & University Rankings" report, showing Houston students don't have to travel out of state to earn a top-notch degree.

WalletHub analyzed 738 colleges and universities in the U.S. using 30 relevant metrics, including factors like student-faculty ratios, graduation rates, and many more. Universities were ranked nationally, regionally, and across seven key dimensions: student selectivity; cost and financing; faculty resources; campus safety; campus experience; educational outcomes; and career outcomes.

Rice also ranked No. 2 in the regional comparison of best universities in the South, and appeared No. 11 nationwide.

Across the seven main categories, the university performed best for its faculty resources (No. 4), education outcomes (No. 11), and student selectivity (No. 16), and earned top-100 rankings for its career outcomes (No. 28) and campus experience (No. 58).

Rice only lagged behind in the national rankings for campus safety (No. 632) and cost and financing (No. 666), but neither category swayed the university's top-performing overall position.

Meanwhile, the University of Houston ranked 75th regionally and 339th nationally. UH's cost and financing rank among the top 200 nationally, landing 177th, and it ranked 284th for its campus safety.This is how the report ranked UH in the five remaining categories out of all 738 schools:
  • No. 306 – Career outcomes
  • No. 324 – Student selectivity
  • No. 343 – Education outcomes
  • No. 383 – Campus experience
  • No. 715 – Faculty resources
Four more local schools ranked among the best universities in the South: Houston Christian University (No. 204), Prairie View A&M University (No. 245), University of Houston-Downtown (No. 251), and Texas Southern University (No. 254).The Houston-area universities, including their graduate and online programs, have earned heaps of national and worldwide praise this year from prestigious educational reviewing authorities U.S. News & World Report and The Princeton Review. Rice University also topped Niche's list of the best Texas universities for 2027.

These are WalletHub's top 10 best colleges and universities in Texas for 2027:

  • No. 1 – Rice University
  • No. 2 – Trinity University
  • No. 3 – The University of Texas at Austin
  • No. 4 – Texas A&M University-College Station
  • No. 5 – Southwestern University
  • No. 6 – University of Dallas
  • No. 7 – Austin College
  • No. 8 – Texas Christian University
  • No. 9 – LeTourneau University
  • No. 10 – The University of Texas at Dallas
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This article first appeared on CultureMap.com.

UH expands Medical Center footprint with $77M research facility

breaking ground

The University of Houston broke ground on a brand new $77.5 million Medical Research Building last week that will host clinical trials and a virtual reality behavioral health suite, among other laboratories. Designed by SmithGroup, it will be the second building on the UH Medical Center campus after the Fertitta College of Medicine opened in 2022.

“The Medical Research Building was designed to foster collaboration and discovery while creating a welcoming environment for students, researchers and the community,” Kalman Nagy, higher education studio design leader for SmithGroup, said in a news release. “As the second building on the University of Houston’s medical campus, we wanted to create a strong connection to the College of Medicine and the surrounding woodlands, with outdoor terraces, shared learning spaces and natural views that inspire interaction and innovation.”

Located just behind the Fertitta building at 5150 Medical Service Drive, the 57,000-square-foot building will house wet laboratories, computational research spaces and specialized facilities for clinical research. The virtual reality behavioral health suite will use immersive technology to deliver care through manufactured audio and visual environments. It’s part of the college’s vision for developing new medical advancements in the heart of Houston’s medical community. The groundbreaking comes on the heels of the launch of the university's cross-disciplinary academic venture, UH Health, this summer.

“This groundbreaking marks an important next step in the growth of the Fertitta College of Medicine and UH Health,” Dr. Jonathan McCullers, vice president for health affairs at UH, added in the release. “We are building the research capacity to match our ambitions—bringing together scientists, physicians and experts from across the University to accelerate discovery and turn promising ideas into solutions that improve people’s lives.”

UH’s journey to establish a significant presence alongside the University of Texas and Baylor in the Medical Center started in 2009 when it became an official full institutional member. The university launched its plans for the Fertitta building in 2013, and is pursuing Health Science Center designation from the Texas Legislature in the next year’s session.

“The research that will take place here will directly benefit our community,” UH President Renu Khator added. “Diseases do not recognize disciplinary silos, and neither should our research. This building will bring together experts from across UH to break down those barriers, work across disciplines and tackle some of our most complex health challenges.”

The building is slated to open in 2028.

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