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’s 10 most valuable startups revealed in new report

by the numbers

The Greater Houston Partnership has released its list of the 10 most valuable startups that are fueling the city’s growth and entrepreneurial energy, including industry giants like Axiom Space and Fervo Energy.

Currently, Houston hosts more than 1,300 startups in industries such as energy, life sciences, manufacturing and aerospace, according to the GHP. The list ranks its top 10 startups by valuation based on the company’s last private funding round, reflected in Pitchbook data, as of Oct. 20 of this year.

The top 10 list includes:

10. NXTClean Fuels

Valuation: $530 million

NXTClean Fuels builds biofuel refineries that produce renewable fuel by using feedstocks like cooking oil and recycled organic materials.

9. Homebase

Valuation: $660 million

HR tech company Homebase provides employee management software that helps manage and optimize timesheets, payroll and more, with over over 100,000 small businesses and 2 million hourly workers using its product.

8. Zolve

Valuation: $800 million

Zolve is a banking platform that provides customers with access to financial products that aim to be accessible, flexible, and affordable than other financial platforms.

7. Stramsen Biotech

Valuation: $807 million

Stramsen Biotech develops plant-based drug therapies that target both infectious and noninfectious diseases, which include cancer, diabetes, HIV, kidney disease and neurological issues.

6. Octagos

Valuation: $843 million

Healthtech company Octagos has developed a remote cardiac monitoring software driven by AI that helps consolidate patient data in real-time, assisting healthcare professionals in providing quicker, easier and more accurate care.

5. Fervo Energy

Valuation: $1.4 billion

Pioneering geothermal company Fervo Energy combines horizontal drilling and fiber-optic sensing to produce electricity. The company is developing its flagship Cape Station geothermal power project in Utah. The first phase of the project will supply 100 megawatts of power beginning in 2026

4.Cart.com

Valuation: $1.7 billion

Cart.com is an e-commerce giant and logistics solutions provider that was founded in 2020 and obtained unicorn status within just three years.

3. Axiom Space

Valuation: $2.1 billion

Axiom Space is one of the anchor tenants at the Houston Spaceport, and has completed four missions of sending commercial astronauts to the ISS since 2022. In 2027, the company expects to see the first section of its private space station, Axiom Station, launched into low-earth orbit.

2. Solugen

Valuation: $2.175 billion

Solugen replaces petroleum-based products with plant-derived substitutes through its Bioforge manufacturing platform.

1. HighRadius

Valuation: $3.2 billion

HighRadius uses advanced technology to automate and manage accounts receivable processes for businesses worldwide.

The GHP also released its State of Houston’s Tech and Innovation Landscape, which mapped Houston’s digital and innovation sectors. Read the full report here.

Photos: Highlights from the 2025 Houston Innovation Awards

Innovation Awards Recap

The 2025 Houston Innovation Awards season came to a close on Nov. 13 at InnovationMap's annual awards program and networking event.

The fifth annual Houston Innovation Awards celebrated more than 40 innovative finalists and crowned 10 winners across prestigious categories. In the weeks leading up to the event, finalists were profiled in our editorial series spotlights. Read all about this year's winners here.

Finalists, judges, and special guests connected during an exclusive VIP reception before the doors officially opened for the evening. A full house of attendees then gathered to celebrate the best and brightest in Houston innovation right now. The night culminated in an awards program, emceed this year by Lawson Gow, Greentown Labs Head of Houston.

Scroll through the photos below for scenes from the event, including the winners, the guests, and more highlights from the program.

Special thanks to this year's sponsors for an unforgettable evening honoring Houston innovation: Houston City College Northwest, Houston Powder Coaters, FLIGHT by Yuengling, William Price Distilling, and Citizens Catering.

2025 Houston Innovation Awards Winners:

Energy Transition Business of the Year: Eclipse Energy. Photo by Emily Jaschke
2025 Houston Innovation Awards Winners:

2025 Houston Innovation Awards Winners, Continued

Minority-founded Business of the Year: Mars Materials. Photo by Emily Jaschke

2025 Houston Innovation Awards Guests 

Photo by Emily Jaschke

More 2025 Houston Innovation Awards Highlights

Photo by Emily Jaschke

Texas ranks among 10 best states to find a job, says new report

jobs report

If you’re hunting for a job in Texas amid a tough employment market, you stand a better chance of landing it here than you might in other states.

A new ranking by personal finance website WalletHub of the best states for jobs puts Texas at No. 7. The Lone Star State lands at No. 2 in the economic environment category and No. 18 in the job market category.

Massachusetts tops the list, and West Virginia appears at the bottom.

To determine the most attractive states for employment, WalletHub compared the 50 states across 34 key indicators of economic health and job market strength. Ranking factors included employment growth, median annual income, and average commute time.

“Living in one of the best states for jobs can provide stable conditions for the long term, helping you ride out the fluctuations that the economy will experience in the future,” WalletHub analyst Chip Lupo says.

In September, Gov. Greg Abbott announced Texas led the U.S. in job creation with the addition of 195,600 jobs over the past 12 months.

“Texas is America’s jobs leader,” Abbott says. “With the best business climate in the nation and a skilled and growing labor force, Texas is where businesses invest, jobs grow, and families thrive. Texas will continue to cut red tape and invest in businesses large and small to spur the economic growth of communities across our great state.”

While Abbott proclaims Texas is “America’s jobs leader,” the state’s level of job creation has recently slowed. In June, the Federal Reserve Bank of Dallas noted that the state’s year-to-date job growth rate had dipped to 1.8 percent, and that even slower job growth was expected in the second half of this year.

The August unemployment rate in Texas stood at 4.1 percent, according to the Texas Workforce Commission. Throughout 2025, the monthly rate in Texas has been either four percent or 4.1 percent.

By comparison, the U.S. unemployment rate in August was 4.3 percent, according to the U.S. Bureau of Labor Statistics. In 2025, the monthly rate for the U.S. has ranged from 4 percent to 4.3 percent.

Here’s a rundown of the August unemployment rates in Texas’ four biggest metro areas:

  • Austin — 3.9 percent
  • Dallas-Fort Worth — 4.4 percent
  • Houston — 5 percent
  • San Antonio — 4.4 percent

Unemployment rates have remained steady this year despite layoffs and hiring freezes driven by economic uncertainty. However, the number of U.S. workers who’ve been without a job for at least 27 weeks has risen by 385,000 this year, the Bureau of Labor Statistics reported in August. That month, long-term unemployed workers accounted for about one-fourth of all unemployed workers.

An August survey by the Federal Reserve Bank of New York showed a record-low 44.9 percent of Americans were confident about finding a job if they lost their current one.
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