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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New manufacturing facility breaks ground at NASA’s Johnson Space Center

making space

HITT Contracting has broken ground on NASA’s Applied Spaceflight Fabrication Facility (ASFF) at Johnson Space Center, the Washington, D.C.-based construction firm announced late last month.

The project, known as Building 70, will house a high-bay machine shop to support component production for future NASA space missions, according to HITT. The 37,625-square-foot building is the first part of a larger goal to create an engineering complex that unites assembly space, lab capabilities and manufacturing at JSC. It will consolidate machining equipment and operations that are currently spread across multiple campus buildings into one location.

The project broke ground in October at JSC’s Historic District. The Houston Business Journal reports construction is expected to wrap in August of 2028.

“This project will modernize facilities that support America’s space missions,” PJ Ross, chief financial officer at HITT, said in a LinkedIn post. “Proud of our team and partners as we begin construction that will advance aerospace testing and innovation.”

HITT Contracting is one of seven companies awarded infrastructure contracts by NASA earlier this year for work at JSC. According to NASA, the construction contracts “[support] up to $300 million in upgrades to mission‑support facilities, utilities, and equipment across the NASA Johnson campus.”

Construction Drive reports that HITT will also renovate Building 13 South on the JSC campus as part of the $300 million initiative.

“Building for precision manufacturing starts with understanding how the space needs to perform,” Todd Hudson, vice president at HITT Contracting, added in the release. “Our team brings the technical expertise and collaborative approach to deliver a facility that meets the Johnson Space Center’s needs today and supports the next generation of spaceflight innovation. We’re proud to continue our partnership with NASA.”

NASA also recently announced awards as part of its expanded Moon Base exploration, science and infrastructure capabilities. Houston-based Intuitive Machines and seven other spacetech companies, including SpaceX, Blue Origin and Firefly Aerospace, were selected to receive funding.

The awards are part of the next phase of NASA’s CLPS (Commercial Lunar Payload Services) initiative, which will grant the companies a combined total of up to $10 billion over 10 years.

Intuitive Machines and Webster-based MEI Technologies were also awarded contracts this past summer from NASA to develop robots for exploring the surface of Mars. Read more here.

Meet 6 mentors guiding Houston’s next generation of startup founders

meet the finalists

Houston’s thriving startup ecosystem is supported by a network of experienced leaders who work behind the scenes, investing their time and knowledge to help the next generation of entrepreneurs succeed.

As part of the 2026 Houston Innovation Awards, the Mentor of the Year category will honor an individual who dedicates their time and expertise to guide and support budding entrepreneurs. They support promising startups in the medical tech, digital health, clean energy, hardware sectors and more.

Read more about these businesses, their founders and their breakthrough technologies below. The 2026 winners will be announced on InnovationMap.com in mid-November.

Al Danto, Rice University

Al Danto is a senior lecturer in entrepreneurship at Rice University. He mentors undergraduate and graduate students at Rice and through the university's Liu Idea Lab for Innovation and Entrepreneurship (Lillie). He's also involved in the Houston Entrepreneurs Organization and Rice Veterans' Business Battle.

"[Mentoring] is very rewarding and fulfilling," Danto says. "[It] helps to me to pay back full circle over the incredible mentors I have had."

Eric Rubenstein, New Climate Ventures

Eric Rubenstein is managing partner at New Climate Ventures. He mentors startups through the clean energy-focused early-stage VC firm and also through the Breakthrough Energy Fellowship, Activate, Greentown Labs and Yale Ventures. Rubenstein has worked with numerous startups and Innovation Awards finalists, including Solidec, Rheom Materials, Bairitone Health, Pattern Materials and many others.

"Being a mentor is an important part of an innovation ecosystem," Rubenstein says. "Seeing founders succeed is rewarding, particularly if what they are building will meaningfully contribute to society. It is a way to give back that also builds community, as mentorship often involves introducing founders to other mentors, to potential investors and to potential customers. Just like the adage 'it takes a village' is used in reference to raising a child, the same adage applies to building a startup. That’s why we say 'let’s build.' Let’s build is inclusive because we do it together, as a community, even if the founders need to execute on a daily basis to make their vision a reality."

Jeremy Pitts, Activate

Jeremy Pitts serves as managing director of Activate Houston, which launched in Houston in 2024. He was one of the founders of Greentown Labs in the Boston area and served in a leadership role for the organization between 2011 and 2015. Through Activate, he has mentored numerous impactful startups and Innovation Awards finalists, including Solidec, Coflux Purification, Bairitone Health, Newfound Materials, Deep Anchor Solutions and others.

"Mentorship to me is all about selflessly supporting a person," Pitts says. "The person comes first--if you're not supporting the person, then their business needs don't matter. I'm there not to answer questions for people, but to help them gain the confidence and the capability to solve problems on their own. I am successful when my mentees are successful and happy, regardless of what their personal definition of success might look like."

Joe Alapat, Liongard

Joe Alapat founded and serves as chief strategy officer at Houston software company Liongard. He founded Startup Circle Houston and co-hosts Cybersecurity Circle, which both meet regularly at The Ion. He participates in Mercury Fund Day and has also mentored through Impact Hub Houston. He's worked with founders of FlowCare, Unytag, STEAM OnDemand, Lokum and many other early-stage startups.

"I compare being a mentor for startup founders to the Montessori method. ... Mentoring should not involve telling a founder what to do," Alapat says. "I see it as a founder whisperer approach that seeks to challenge the founder to think through their journey through different lenses and go on a journey of self-discovery while discovering the true market pain they are seeking to solve. The cherry on top is that the mentor gains as much as the mentee, so learning is happening for both. Ultimately, the meter of achievement with mentoring is seeing visible progress with the maturity of the founder and the degree of traction for their startup."

Kyle Judah, Rice University's Liu Idea Lab for Innovation & Entrepreneurship

Kyle Judah is the executive director of Lilie, where he mentors pre-seed student startups. He also mentors through organizations like TEX-E, Greentown Labs, Activate and previously with MassChallenge. Some of the startups he's mentored include Helix Earth Technologies, Tierra Climate, Solidec, HexaSpec, SteerBio and many others.

"[Being a mentor] means helping to ensure that the most people possible have the best shot possible at making their company a successful reality," Judah says. "It means, at its root, opening the aperture for what is possible for people, by believing in them before anyone else even understands what their ambitions are. Because belief is the most infectious thing in the world. And before digging into the work in the trenches, most times founders need to kickstart their journey by having someone from the outside believe in them, when there's no real evidence to support that belief. So I guess, mentorship is a pure form of entrepreneurial faith."

Rachel Bickham, Bickham Services Unlimited LLC

Rachel Bickham is CEO of Bickham Services Unlimited, through which she mentors founders across a range of business stages and industries. She founded the organization in 2017. Bickham also mentors through The Affirmed Entrepreneur, a mentorship platform that she also launched. In 2024, she also began mentoring through the Goldman Sachs One Million Black Women: Black in Business program. Some of the startups she has worked with included Elaine Transportation, Nakira's World and NP Skills Made Easy, among others.

"Being a mentor means helping someone see what is possible while being honest about what it will take to get there," Bickham says. "It is not about giving generic advice or telling entrepreneurs what they want to hear. Sometimes mentorship means offering encouragement, and sometimes it means asking difficult questions that help someone avoid an expensive mistake. In both situations, my responsibility is to listen, share what I have learned, and help the entrepreneur make an informed decision. ... Being a mentor also means opening doors when I can—making introductions, inviting entrepreneurs into rooms they may not have entered on their own, and helping them build relationships that can change the direction of their businesses. It also means holding them accountable for what they said they wanted to accomplish. I do not measure successful mentorship by how often someone returns to me for an answer. I measure it by whether they become more confident, more strategic, and better equipped to make decisions on their own."

3 Houston incubators and accelerators fueling the growth of local startups

Meet the finalists

It takes a village to launch a business. That's where Houston's network of incubators and accelerators can step in, providing the resources, mentorship and community needed to push a fledgling company forward.

As part of our 2026 Houston Innovation Awards, the Incubator/Accelerator of the Year category honors a local organization that is championing and fueling the growth of Houston startups.

Three incubators and accelerators have been named finalists for the 2026 award. They support startups ranging from hard-tech companies to food and youth concepts.

Read more about these organizations below. The 2026 winners will be announced on InnovationMap.com in mid-November.

Activate

Hard tech incubator Activate supports scientists in "the outset of their entrepreneurial journey." The Houston hub was introduced in 2024, and joins others in Boston, New York, and Berkley, California—where Activate is headquartered. It named its third Houston cohort this summer.

The two-year program graduated its first class of Houston fellows in 2026 and saw its first alumni IPO from Houston-based Fervo Energy, which previously participated in a Berkley cohort. Nationally, it has supported 346 fellows and 276 companies since 2015. Those companies have raised more than $6 billion in follow-on funding, according to Activate. In Houston, it has supported Houston startups like Solidec, FlowCellutions and Orbital Arc. Activate Houston is led by managing director Jeremy Pitts, who co-founded Greentown Labs in Boston. It is based out of the Ion.

Impact Hub Houston

Impact Hub Houston supports early-stage ventures at various stages of development through innovative programs that address pressing societal issues. The nonprofit organization supports social impact startups through mentorship, connections and training opportunities.

There are more than 110 Impact Hubs globally with members spanning 72 countries. Launched in 2018, Impact Hub Houston says its membership tripled by the beginning of 2026. This year brought major milestones for the community, including the launch of its Ideas to Impact Accelerator, which supported 11 founders across the health, education, food systems, civic technology and workforce development sectors. It also received funding from more than 20 international Impact Hubs to develop SYNC, a collaboration platform that 25 Impact Hubs across five continents have committed to pilot. The organization has worked with local startups including Myoviva Health, The Change Lab and INNERVERSE Inc.

MarMo Innovation

Galveston-based business incubator MarMo Innovation is focused on removing barriers to entrepreneurship. It aims to provide affordable space, education, mentorship, market access, connections and real-world opportunities that help entrepreneurs move from idea to launch to sustainable growth. The "industry-agnostic" incubator was founded in 2022 and is led by Executive Director Erica Delgadillo.

This year, the organization moved from primarily serving as a coworking and community space into a more comprehensive entrepreneurial incubator by expanding its MarMo Market, MarMo Market Jr. and Lunch LineUp programs. A major focus for MarMo is food entrepreneurship. It is developing an Incubator Kitchen, which MarMo says will support programs like its Cottage to Commercial Bootcamp and Food Biz 101. The organization also expanded its board this year and says it is diversifying its revenue through memberships, events, markets, equipment and space rentals, sponsorships, grants and new entrepreneurial programming.

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