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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2 Texas cities named on LinkedIn's inaugural 'Cities on the Rise'

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LinkedIn’s 2025 Cities on the Rise list includes two Texas cities in the top 25—and they aren’t Houston or Dallas.

The Austin metro area came in at No. 18 and the San Antonio metro at No. 23 on the inaugural list that measures U.S. metros where hiring is accelerating, job postings are increasing and talent migration is “reshaping local economies,” according to the company. The report was based on LinkedIn’s exclusive labor market data.

According to the report, Austin, at No. 18, is on the rise due to major corporations relocating to the area. The datacenter boom and investments from tech giants are also major draws to the city, according to LinkedIn. Technology, professional services and manufacturing were listed as the city’s top industries with Apple, Dell and the University of Texas as the top employers.

The average Austin metro income is $80,470, according to the report, with the average home listing at about $806,000.

While many write San Antonio off as a tourist attraction, LinkedIn believes the city is becoming a rising tech and manufacturing hub by drawing “Gen Z job seekers and out-of-state talent.”

USAA, U.S. Air Force and H-E-B are the area’s biggest employers with professional services, health care and government being the top hiring industries. With an average income of $59,480 and an average housing cost of $470,160, San Antonio is a more affordable option than the capital city.

The No. 1 spot went to Grand Rapids due to its growing technology scene. The top 10 metros on the list include:

  • No. 1 Grand Rapids, Michigan
  • No. 2 Boise, Idaho
  • No. 3 Harrisburg, Pennsylvania
  • No. 4 Albany, New York
  • No. 5 Milwaukee, Wisconsin
  • No. 6 Portland, Maine
  • No. 7 Myrtle Beach, South Carolina
  • No. 8 Hartford, Connecticut
  • No. 9 Nashville, Tennessee
  • No. 10 Omaha, Nebraska

See the full report here.

Houston Methodist receives $25M gift, renames department of medicine

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Houston-based nonprofit The Duncan Fund has awarded a $25 million gift to Houston Methodist's department of medicine to establish new endowed fellowships, streamline complex care and bring artificial intelligence into the fold to develop more personalized treatment plans.

In turn, the health care system announced that it will rename the department the Charles W. Duncan Jr. Department of Medicine at Houston Methodist.

“We are deeply appreciative of the Duncan family’s support, which allows us to further programs at the intersection of personalized medicine and preventive health care to benefit our patients,” Dr. Eleftherios Mylonakis, chair of the department and the Charles and Anne Duncan Presidential Distinguished Chair, said in a news release.

The department of medicine is Houston Methodist's largest, and comprises 13 clinical programs, ranging from general medicine to highly specialized care, as well as research and education.

According to Houston Methodist, the latest grant from the Duncan family will:
  • Coordinate complex, multidisciplinary care by hospitalists
  • Implement programs that leverage data and AI to tailor treatments and preventive strategies
  • Establish five endowed fellowships, including a new fellowship for students known as MedTech Innovator

“Our vision is to redefine how care is delivered in our country by creating a national model for true continuity — one that follows the patient across every transition, from home to hospital and back again,” Mylonakis added in the release. “We are also advancing a deeper understanding of health span, shifting from reactive treatment to a proactive, lifelong strategy that maximizes not just how long we live but how well we live.”

The Duncan family has been a longtime supporter of Houston Methodist—and Houston organizations at large. The late Charles Duncan Jr. sat on the system's board for decades, and his son, Charles “Carlos” Duncan III, serves on the Houston Methodist Hospital Foundation Board. Additionally, the family established the Charles and Anne Duncan Scholars Program and endowed chairs in nephrology and endocrinology.

Charles Duncan Jr. is also the namesake behind Rice University's Duncan Residential College and was one of the founders of the Greater Houston Partnership. He served as Secretary of Energy during the Carter Administration.

New York Stock Exchange Texas announces location for Dallas headquarters

NYSE Texas

A location has been chosen for The New York Stock Exchange Texas, the new Dallas-based offshoot of the The New York Stock Exchange in New York.

According to a release, the NYSE Texas has leased 28,000 square-feet of space at Old Parkland, the hospital-turned office space at 3819 Maple Ave. in Oak Lawn, where it will operate as a fully electronic equities exchange headquartered in Dallas. The property is owned by Dallas billionaire Harlan Crowe, who acquired it in 2006.

The NYSE is part of the Intercontinental Exchange, Inc., a global provider of technology and data. It was previously the NYSE Chicago, which will close once the bureau in Texas debuts.

They’ve also named a president to the Texas branch: Bryan Daniel, former chairman of the Texas Workforce Commission. In his new role over the NYSE Texas, Daniel will report to President of NYSE Group Lynn Martin.

Relocating from Chicago to Texas was a response to Texas' pro-business profile, Martin says in a statement.

“As the state with the largest number of NYSE listings, representing over $3.7 trillion in market value for our community, Texas is a market leader in fostering a pro-business atmosphere,” Martin says. “We are delighted to expand our presence in the Lone Star State, which plays a key role in driving our U.S. economy forward.”'

The move comes five months after the Texas Stock Exchange — AKA TXSE — announced plans to launch in Dallas and begin trading in 2026, pending approval from the U.S. Securities and Exchange Commission. The Texas Stock Exchange is backed by financial giants such as BlackRock, Citadel Securities, and Charles Schwab.

The NYSE expects the Texas location to open in 2026, where it will operate electronically, with stocks trading across multiple venues regardless of where they are first listed, according to the release.

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This article originally appeared on CultureMap.com.

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