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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Rice University launches new center to study roots of Alzheimer’s and Parkinson’s

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Rice University launched its new Amyloid Mechanism and Disease Center last month, which aims to uncover the molecular origins of Alzheimer’s, Parkinson’s and other amyloid-related diseases.

The center will bring together Rice faculty in chemistry, biophysics, cell biology and biochemistry to study how protein aggregates called amyloids form, spread and harm brain cells. It will serve as the neuroscience branch of the Rice Brain Institute, which was also recently established.

The team will work to ultimately increase its understanding of amyloid processes and will collaborate with the Texas Medical Center to turn lab discoveries into real progress for patients. It will hold its launch event on Jan. 21, 2026, and hopes to eventually be a launchpad for future external research funding.

The new hub will be led by Pernilla Wittung-Stafshed, a Rice biophysicist and the Charles W. Duncan Jr.-Welch Chair in Chemistry.

“To make a real difference, we have to go all the way and find a cure,” Wittung-Stafshede said in a news release. “At Rice, with the Amyloid Mechanism and Disease Center as a catalyst, we have the people and ideas to open new doors toward solutions.”

Wittung-Stafshede, who was recruited to Rice through a Cancer Prevention and Research Institute of Texas grant this summer, has led pioneering work on how metal-binding proteins impact neurodegenerative disorders, including Alzheimer’s and Parkinson’s diseases. Her most recent study, published in Advanced Science, suggests a new way of understanding how amyloids may harm cells and consume the brain’s energy molecule, ATP.

According to Alzheimer’s Disease International, neurodegenerative disease cases could reach around 78 million by 2030 and 139 million by 2050. Wittung-Stafshede’s father died of dementia several years ago.

“This is close to my heart,” Wittung-Stafshede added in the news release. “Neurodegenerative diseases such as dementia, Alzheimer’s and Parkinson’s are on the rise as people live longer, and age is the largest risk factor. It affects everyone.”

This Houston airport saw sharp passenger decline in 2025, study shows

Travel Talk

A new global airport travel study has revealed passenger traffic at Houston's William P. Hobby Airport (HOU) sharply decreased from 2024 to 2025.

The analysis from travel magazine LocalsInsider examined recently released data from the Bureau of Transportation Statistics (BTS), the U.S. International Trade Association, and a nationwide survey to determine the following American traveler habits: The most popular U.S. and international destinations, emerging hotspots, and destinations on the decline. The study covered passenger travel trends from January through July 2025.

In the report's ranking of the 40 U.S. airports with the sharpest declines in passenger traffic, HOU ranked 13th on the list.

About 4.26 million arrivals were reported at HOU from January through July 2024, compared to about 3.96 million during the same seven-month period in 2025. According to the data, that's a significant 7.1 percent drop in passenger traffic year-over-year, or a loss of 300,974 passengers.

"As travelers chase new hotspots, some destinations are seeing reduced passenger traffic whether due to rising costs, shifting airline schedules, or evolving traveler preferences, some destinations are seeing a decrease in visitors," the report's author wrote.

It appears most major Texas airports had drops in passenger traffic from 2024 to 2025. Dallas Love Field Airport (DAL) saw the worst in the state, with a dramatic 7.4 percent dip in arrivals. DAL also ranked 11th on the list of U.S. airports with the steepest declines in passenger traffic.

More than 5.13 million arrivals were reported at DAL from January through July 2024, compared to over 4.75 million during the same seven-month period in 2025.

This is how passenger traffic has fallen at other major Texas airports from 2024 to 2025:

Austin-Bergstrom International Airport (AUS):

  • 6,107,597 – Passenger arrivals from January to July 2024
  • 5,828,396 – Passenger arrivals from January to July 2025
  • -4.6 percent – Year-over-year passenger change
Dallas/Fort Worth International Airport (DFW):
  • 23,830,017 – Passenger arrivals from January to July 2024
  • 23,251,302 – Passenger arrivals from January to July 2025
  • -2.4 percent – Year-over-year passenger change

San Antonio International Airport (SAT):

  • 2,937,870 – Passenger arrivals from January to July 2024
  • 2,836,774 – Passenger arrivals from January to July 2025
  • -3.4 percent – Year-over-year passenger change
El Paso International Airport (ELP):
  • 1,094,431 – Passenger arrivals from January to July 2024
  • 1,076,845 – Passenger arrivals from January to July 2025
  • -1.6 percent – Year-over-year passenger change
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This story originally appeared on CultureMap.com.

NASA names new chief astronaut based in Houston

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NASA has a new chief astronaut. Scott Tingle, stationed at the space agency’s Johnson Space Center in Houston, assumed the post Nov. 10.

Tingle succeeds NASA astronaut Joe Acaba, who had been chief astronaut since February 2023. Acaba now works on the staff of the Johnson Space Center’s director.

As chief astronaut, Tingle runs NASA’s Astronaut Office. His job includes developing astronauts’ flight crew operations and assigning crews for space missions, such as Artemis missions to the moon.

Tingle, a former captain in the Navy, was named a NASA astronaut candidate in 2009. He has logged over 4,500 flight hours in more than 50 aircraft.

Tingle was a flight engineer aboard the International Space Station, where he spent 168 days in orbit during two expeditions that launched in December 2017. Since returning to Earth, he has held various roles in the Astronaut Office, including mission support, technical leadership and crew readiness.

Before joining NASA, Tingle worked in El Segundo, California, on the technical staff of The Aerospace Corp., a nonprofit that supports U.S. space programs.

Tingle recalls expressing his desire to be an astronaut when he was 10 years old. It took him four tries to be accepted by NASA as an astronaut candidate.

“The first time I figured it was kind of too early. The second application, they sent out some feelers, and that was about it. Put in my third application, and got a couple of calls, but it didn’t quite happen,” Tingle said in an article published on the website of Purdue University, his alma mater.

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