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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New Rice Brain Institute partners with TMC to award inaugural grants

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The recently founded Rice Brain Institute has named the first four projects to receive research awards through the Rice and TMC Neuro Collaboration Seed Grant Program.

The new grant program brings together Rice faculty with clinicians and scientists at The University of Texas Medical Branch, Baylor College of Medicine, UTHealth Houston and The University of Texas MD Anderson Cancer Center. The program will support pilot projects that address neurological disease, mental health and brain injury.

The first round of awards was selected from a competitive pool of 40 proposals, and will support projects that reflect Rice Brain Institute’s research agenda.

“These awards are meant to help teams test bold ideas and build the collaborations needed to sustain long-term research programs in brain health,” Behnaam Aazhang, Rice Brain Institute director and co-director of the Rice Neuroengineering Initiative, said in a news release.

The seed funding has been awarded to the following principal investigators:

  • Kevin McHugh, associate professor of bioengineering and chemistry at Rice, and Peter Kan, professor and chair of neurosurgery at the UTMB. McHugh and Kan are developing an injectable material designed to seal off fragile, abnormal blood vessels that can cause life-threatening bleeding in the brain.
  • Jerzy Szablowski, assistant professor of bioengineering at Rice, and Jochen Meyer, assistant professor of neurology at Baylor. Szablowski and Meyer are leading a nonsurgical, ultrasound approach to deliver gene-based therapies to deep brain regions involved in seizures to control epilepsy without implanted electrodes or invasive procedures.
  • Juliane Sempionatto, assistant professor of electrical and computer engineering at Rice, and Aaron Gusdon, associate professor of neurosurgery at UTHealth Houston. Sempionatto and Gusdon are leading efforts to create a blood test that can identify patients at high risk for delayed brain injury following aneurysm-related hemorrhage, which could lead to earlier intervention and improved outcomes.
  • Christina Tringides, assistant professor of materials science and nanoengineering at Rice, and Sujit Prabhu, professor of neurosurgery at MD Anderson, who are working to reduce the risk of long-term speech and language impairment during brain tumor removal by combining advanced brain recordings, imaging and noninvasive stimulation.

The grants were facilitated by Rice’s Educational and Research Initiatives for Collaborative Health (ENRICH) Office. Rice says that the unique split-funding model of these grants could help structure future collaborations between the university and the TMC.

The Rice Brain Institute launched this fall and aims to use engineering, natural sciences and social sciences to research the brain and reduce the burden of neurodegenerative, neurodevelopmental and mental health disorders. Last month, the university's Shepherd School of Music also launched the Music, Mind and Body Lab, an interdisciplinary hub that brings artists and scientists together to study the "intersection of the arts, neuroscience and the medical humanities." Read more here.

Your data center is either closer than you think or much farther away

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A new study shows why some facilities cluster in cities for speed and access, while others move to rural regions in search of scale and lower costs. Based on research by Tommy Pan Fang (Rice Business) and Shane Greenstein (Harvard).

Key findings:

  • Third-party colocation centers are physical facilities in close proximity to firms that use them, while cloud providers operate large data centers from a distance and sell access to virtualized computing resources as on‑demand services over the internet.
  • Hospitals and financial firms often require urban third-party centers for low latency and regulatory compliance, while batch processing and many AI workloads can operate more efficiently from lower-cost cloud hubs.
  • For policymakers trying to attract data centers, access to reliable power, water and high-capacity internet matter more than tax incentives.

Recent outages and the surge in AI-driven computing have made data center siting decisions more consequential than ever, especially as energy and water constraints tighten. Communities invest public dollars on the promise of jobs and growth, while firms weigh long-term commitments to land, power and connectivity.

Against that backdrop, a critical question comes into focus: Where do data centers get built — and what actually drives those decisions?

A new study by Tommy Pan Fang (Rice Business) and Shane Greenstein (Harvard Business School) provides the first large-scale statistical analysis of data center location strategies across the United States. It offers policymakers and firms a clearer starting point for understanding how different types of data centers respond to economic and strategic incentives.

Forthcoming in the journal Strategy Science, the study examines two major types of infrastructure: third-party colocation centers that lease server space to multiple firms, and hyperscale cloud centers owned by providers like Amazon, Google and Microsoft.

Two Models, Two Location Strategies

The study draws on pre-pandemic data from 2018 and 2019, a period of relative geographic stability in supply and demand. This window gives researchers a clean baseline before remote work, AI demand and new infrastructure pressures began reshaping internet traffic patterns.

The findings show that data centers follow a bifurcated geography. Third-party centers cluster in dense urban markets, where buyers prioritize proximity to customers despite higher land and operating costs. Cloud providers, by contrast, concentrate massive sites in a small number of lower-density regions, where electricity, land and construction are cheaper and economies of scale are easier to achieve.

Third-party data centers, in other words, follow demand. They locate in urban markets where firms in finance, healthcare and IT value low latency, secure storage, and compliance with regulatory standards.

Using county-level data, the researchers modeled how population density, industry mix and operating costs predict where new centers enter. Every U.S. metro with more than 700,000 residents had at least one third-party provider, while many mid-sized cities had none.

ImageThis pattern challenges common assumptions. Third-party facilities are more distributed across urban America than prevailing narratives suggest.

Customer proximity matters because some sectors cannot absorb delay. In critical operations, even slight pauses can have real consequences. For hospital systems, lag can affect performance and risk exposure. And in high-frequency trading, milliseconds can determine whether value is captured or lost in a transaction.

“For industries where speed is everything, being too far from the physical infrastructure can meaningfully affect performance and risk,” Pan Fang says. “Proximity isn’t optional for sectors that can’t absorb delay.”

The Economics of Distance

For cloud providers, the picture looks very different. Their decisions follow a logic shaped primarily by cost and scale. Because cloud services can be delivered from afar, firms tend to build enormous sites in low-density regions where power is cheap and land is abundant.

These facilities can draw hundreds of megawatts of electricity and operate with far fewer employees than urban centers. “The cloud can serve almost anywhere,” Pan Fang says, “so location is a question of cost before geography.”

The study finds that cloud infrastructure clusters around network backbones and energy economics, not talent pools. Well-known hubs like Ashburn, Virginia — often called “Data Center Alley” — reflect this logic, having benefited from early network infrastructure that made them natural convergence points for digital traffic.

Local governments often try to lure data centers with tax incentives, betting they will create high-tech jobs. But the study suggests other factors matter more to cloud providers, including construction costs, network connectivity and access to reliable, affordable electricity.

When cloud centers need a local presence, distance can sometimes become a constraint. Providers often address this by working alongside third-party operators. “Third-party centers can complement cloud firms when they need a foothold closer to customers,” Pan Fang says.

That hybrid pattern — massive regional hubs complementing strategic colocation — may define the next phase of data center growth.

Looking ahead, shifts in remote work, climate resilience, energy prices and AI-driven computing may reshape where new facilities go. Some workloads may move closer to users, while others may consolidate into large rural hubs. Emerging data-sovereignty rules could also redirect investment beyond the United States.

“The cloud feels weightless,” Pan Fang says, “but it rests on real choices about land, power and proximity.”

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This article originally appeared on Rice Business Wisdom. Written by Scott Pett.

Pan Fang and Greenstein (2025). “Where the Cloud Rests: The Economic Geography of Data Centers,” forthcoming in Strategy Science.

Houston climbs to top 10 spot on North American tech hubs index

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Houston already is the Energy Capital of the World, and now it’s gaining ground as a tech hub.

On Site Selection magazine’s 2026 North American Tech Hub Index, Houston jumped to No. 10 from No. 16 last year. The index relies on data from Site Selection as well as data from CBRE, CompTIA and TeleGeography to rank the continent’s tech hotspots. The index incorporates factors such as internet connectivity, tech talent and facility projects for tech companies.

In 2023, the Greater Houston Partnership noted the region had “begun to receive its due as a prominent emerging tech hub, joining the likes of San Francisco and Austin as a major player in the sector, and as a center of activity for the next generation of innovators and entrepreneurs.”

The Houston-area tech sector employs more than 230,000 people, according to the partnership, and generates an economic impact of $21.2 billion.

Elsewhere in Texas, two other metros fared well on the Site Selection index:

  • Dallas-Fort Worth nabbed the No. 1 spot, up from No. 2 last year.
  • Austin rose from No. 8 last year to No. 7 this year.

San Antonio slid from No. 18 in 2025 to No. 22 in 2026, however.

Two economic development officials in DFW chimed in about the region’s No. 1 ranking on the index:

  • “This ranking affirms what we’ve long seen on the ground — Dallas-Fort Worth is a top-tier technology and innovation center,” said Duane Dankesreiter, senior vice president of research and innovation at the Dallas Regional Chamber. “Our region’s scale, talent base, and diverse strengths … continue to set DFW apart as a national leader.”
  • “Being recognized as the top North American tech hub underscores the strength of the entire Dallas-Fort Worth region as a center of innovation and next-generation technology,” said Robert Allen, president and CEO of the Fort Worth Economic Development Partnership.

While not directly addressing Austin’s Site Selection ranking, Thom Singer, CEO of the Austin Technology Council, recently pondered whether Silicon Hills will grow “into the kind of community that other cities study for the right reasons.”

“Austin tech is not a club. It is not a scene. It is not a hashtag, a happy hour, or any one place or person,” Singer wrote on the council’s blog. “Austin tech is an economic engine and a global brand, built by thousands of people who decided to take a risk, build something, hire others, and be part of a community that is still young enough to reinvent itself.”

South of Austin, Port San Antonio is driving much of that region’s tech activity. Occupied by more than 80 employers, the 1,900-acre tech and innovation campus was home to 18,400 workers in 2024 and created a local economic impact of $7.9 billion, according to a study by Zenith Economics.

“Port San Antonio is a prime example of how innovation and infrastructure come together to strengthen [Texas’] economy, support thousands of good jobs, and keep Texas competitive on the global stage,” said Kelly Hancock, the acting state comptroller.