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 medtech startup clears FDA approval for new surgical tool

precision surgery

Houston-based Prana Surgical will soon bring a new electrosurgical tool to operating rooms around the country. The Prana System officially cleared U.S. Food and Drug Administration (FDA) approval earlier this month.

"Receiving FDA clearance for the Prana System represents a defining milestone for our company," Joanna Nathan, CEO and co-founder of Prana Surgical, said in a news release. "Surgeons today are increasingly focused on achieving precise outcomes while minimizing disruption to healthy tissue. The Prana System was designed to support that shift by integrating targeting and excision into a single, streamlined tool."

Prana Surgical began as Prana Thoracic in 2022. Back then, the company primarily focused on developing screening tools for lung cancer diagnosis. It raised $6 million in series A funding rounds in 2023 and 2024 before transitioning to broader surgical needs in 2025.

The Prana System is a minimally invasive, image-guided, single-use tissue extraction tool designed to retrieve samples without damaging healthy tissue. The tool is still designed with the respiratory system in mind, helping Prana in the fight against lung cancer and other thoracic diseases.

Reducing the impact of tissue extraction via electrosurgery and enhanced image scanning can significantly reduce complications. The Prana System combines localization and tissue-cutting capabilities in one, which keeps surgeons from having to swap out components during a procedure, making for a smoother process. It can core, cut and feel blood vessels on the way toward the intended target, giving surgeons greater control over tissue preservation.

"Electrosurgery is foundational to modern surgery, but there is still opportunity to improve how energy-based tools are applied in minimally invasive settings," Nathan added. "Our goal is to introduce a new class of image-guided surgical tools that enable more precise intervention across a range of procedures."

The company projects sales of $7.5 billion from the Prana System in the United States, estimating that 2.5 million surgical modules will be able to use the new tool. While starting out focused on biopsies, the company plans to evolve the system into other procedures, such as ablation, in the future. It is also planning for a controlled U.S. clinical rollout as it moves toward commercialization

Texas still ranks as No. 1 in U.S. for inbound moves, but growth dips

by the numbers

Texas continues to be the country’s No. 1 magnet for newcomers from other states, giving a boost to the state’s economy. However, Texas’ appeal weakened in 2024 compared with the previous year, due in large part to spiking home prices.

An analysis of U.S. Census Bureau data by self-storage platform StorageCafe shows Texas saw net interstate migration of 76,000 people in 2024. Texas’ net interstate migration dropped nearly 50 percent from 2023, according to the analysis. Net migration refers to the number of incoming residents minus the number of outgoing residents.

California remained the top source of newcomers for Texas, sending nearly 77,000 residents to the Lone Star State in 2024, the analysis says. Florida ranked second, followed by New York, Colorado and Illinois.

“These trends reveal Texas’ continued pull from both high-cost coastal markets and other large Sun Belt states, resulting in a mix of affordability-driven and job-driven relocation,” StorageCafe says.

Putting a damper on the influx of new residents: a roughly 124 percent surge in Texas home prices over the past decade, according to StorageCafe.

“While the state remains significantly more affordable than California, its top feeder state, the once-wide pricing gap has narrowed,” says StorageCafe. “For many movers, Texas is still a relative bargain, but no longer an undisputed one.”

Nonetheless, Texas keeps attracting young, highly educated people, which bodes well for the state’s long-term economic outlook, StorageCafe says. More than half of new arrivals to Texas in 2024 held at least a bachelor’s degree, and the age of newcomers averaged 32.

Where are most of these young, highly educated newcomers settling?

Lloyd Potter, former Texas state demographer, tells StorageCafe that population growth in Texas is happening most rapidly in suburban “ring counties” at the expense of slowing growth in urban cores. Ring counties are on the outskirts of major metro areas.

“Many people are moving from urban cores to suburban rings seeking lower costs, newer housing, better schools, and more space,” Potter says. “Typically, a move to a suburban county will be within commuting or hybrid‑commuting distance of major metro economies.”

Artemis II makes historic call to space station with help from Houston Mission Control

History in the making

Still aglow from their triumphant lunar flyby, the Artemis II astronauts made more history Tuesday, April 7: calling their friends aboard the International Space Station hundreds of thousands of miles away as they headed home from the moon.

It was the first moonship-to-spaceship radio linkup ever. NASA's Apollo crews had no off-the-planet company back in the 1960s and 1970s, the last time humanity set sail for deep space.

"We have been waiting for this like you can’t imagine,” Artemis II commander Reid Wiseman called out.

For Christina Koch on Artemis II and Jessica Meir aboard the space station, it marked a joyous space reunion despite being 230,000 miles (370,000 kilometers) apart. The two teamed up for the world's first all-female spacewalk in 2019 outside the orbiting lab.

Koch told her “astro-sister” that she'd hoped to meet up with her again in space “but I never thought it would be like this — it's amazing.”

“I'm so happy that we are back in space together,” Meir replied, “even if we are a few miles apart.”

Houston's Mission Control arranged the cosmic chitchat between the four lunar travelers and the space station's three NASA and one French residents.

Koch described being awe-struck by not just the beauty of Earth, “but how much blackness there was around it.”

“It just made it even more special. It truly emphasized how alike we are, how the same thing keeps every single person on planet Earth alive,” she told the space station crew. “The specialness and preciousness of that really is emphasized” when viewing the home planet from the moon.

By late Tuesday afternoon, the Artemis II astronauts had beamed back more than 50 gigabytes' worth of pictures and other data from the previous day's lunar rendezvous, which set a new distance record for humanity. The highlight: an Earthset photo reminiscent of Apollo 8's Earthrise shot from 1968.

"While they are inspirational and, I think, allow all of us to really feel a little bit of what they were feeling, there's also a lot of science hidden inside of those images," said Mission Control's lead lunar scientist Kelsey Young. “The conversations and the science lessons learned are just beginning."

During a debriefing with Young, the astronauts recounted how they spotted a cascade of pinpricks of light on the lunar surface from impacting cosmic debris. The flashes lasted mere milliseconds and coincided by chance with Monday evening's total solar eclipse.

Young said it was too soon to know whether the crew witnessed an actual meteor shower or more random, run-of-the-mill micrometeoroid hits. Either way, there were “audible screams of delight” in the science operations center, she said.

Koch described being awe-struck by not just the beauty of Earth, “but how much blackness there was around it.”

“It just made it even more special. It truly emphasized how alike we are, how the same thing keeps every single person on planet Earth alive,” she told the space station crew. “The specialness and preciousness of that really is emphasized” when viewing the home planet from the moon.

The first lunar explorers since Apollo 17 in 1972, Wiseman and his crew are aiming for a splashdown off the San Diego coast on Friday to wrap up the nearly 10-day test flight. The recovery ship USS John P. Murtha left port Tuesday for the target zone.

It sets the stage for next year's Artemis III, a lunar lander docking demo in orbit around Earth. Artemis IV will follow in 2028 with two astronauts attempting to land near the lunar south pole.

As for the Orion capsule’s pesky potty, Mission Control assured the astronauts that no maintenance was required Tuesday. The toilet has been on-and-off limits to the crew ever since last week’s launch, prompting them to rely on a backup bag-and-funnel system for urinating.

NASA Administrator Jared Isaacman told the crew following the lunar flyby Monday night: “We definitely have to fix some of the plumbing” ahead of the next Artemis mission. Engineers suspect a clogged filter in the overboard flushing system.

Aside from the toilet and other relatively minor matters, the mission has gone well, Isaacman noted at a news conference Tuesday, “but I'll breathe easier when we get through reentry and everybody's under chutes and in the water.”

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