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 Alliance names Houston healthtech exec as first head of platform

new hire

The Rice Alliance for Technology and Entrepreneurship has named its first head of platform.

Houston entrepreneur Laura Neder stepped into the newly created role last month, according to an email from Rice Alliance. Neder will focus on building and growing Houston’s Venture Advantage Platform.

The emerging platform, which is being promoted by Rice Alliance and the Ion, aims to connect founders with the "people, capital and expertise they need to scale."

"I’ve spent a lot of time thinking about what it takes to make an innovation ecosystem more navigable, more connected, and more useful for founders," Neder said in a LinkedIn post. "I’m grateful for the opportunity to do that work at Rice Alliance, alongside a team with a long history of supporting entrepreneurship and innovation."

"Houston has the talent, institutions, and industry base to create real advantage for founders," she added. "I’m looking forward to listening, learning, and building stronger pathways across the ecosystem."

Neder most recently served as CEO of Houston-based Careset, where she helped bring the Medicare data startup to commercialization. Prior to that, Neder served as COO of Houston-based telemedicine startup 2nd.MD, which was acquired for $460 million by Accolade in 2021.

"Laura brings a rare combination of founder empathy, operational experience and ecosystem leadership," Rice Alliance shared.

Neder and Rice Alliance also shared that the organization is hiring developers to design the new Venture Advantage Platform. Learn more here.

Elon Musk's SpaceX files initial paperwork to sell shares to the public

Incoming IPO

Elon Musk's space exploration company has filed preliminary paperwork to sell shares to the public, according to two sources familiar with the filing, a blockbuster offering that would likely rank as the biggest ever and could make its founder the world's first trillionaire.

A SpaceX IPO promises to be one of the biggest Wall Street events of the year, with several investment banks lining up to help raise tens of billions to fund Musk's ambitions to set up a base on the moon, put datacenters the size of several football fields in orbit and possibly one day send a man to Mars.

The sources spoke on condition of anonymity because they were not authorized to talk publicly about the confidential registration with the Securities and Exchange Commission.

SpaceX did not respond immediately to a request for comment.

Exactly how much SpaceX plans to raise has not been disclosed but the figure is reportedly as much as $75 billion. At that level, the offering would easily eclipse the $29 billion that Saudi Aramco raised in its IPO in 2019.

The offering, coming possibly in June, could value all the shares of SpaceX at $1.5 trillion, nearly double what the company was valued in December when some minority owners sold their stakes, according to research firm Pitchbook, before an acquisition that increased its size.

Musk owns 42% of the SpaceX now, according to Pitchbook, though that figure will change with the IPO when new owners are issued shares. In any case, he is likely to pierce the trillion dollar mark because he is already close. Forbes magazine estimates Musk's net worth at roughly $823 billion.

In addition to making reusable rockets to hurl astronauts and hardware into orbit, SpaceX owns Starlink, the world’s largest satellite communications company. The company also recently brought under its roof two other Musk businesses, social media platform X, formerly Twitter, and artificial intelligence business, xAI, in a controversial transaction because both the seller and the buyer were controlled by him.

SpaceX has become the biggest commercial launch company in its industry, responsible for sending payloads into orbit for customers across the globe, but has also benefited from big taxpayer spending. That has raised conflicts of interest issues given that Musk was the biggest donor to President Donald Trump's campaign and is still a big backer.

In the past five years, SpaceX won $6 billion in contracts from NASA, the Defense Department and other U.S. government agencies, according to USAspending.gov.

Among current SpaceX owners is Donald Trump Jr, the president's oldest son. He owns a shares through 1789 Capital. That venture capital firm made him a partner shortly after his father won the presidency for a second time and has been buying up federal contractors seeking to win taxpayer money ever since.

The White House and Trump himself have repeatedly denied there are any conflicts of interest between his role as president and his family's businesses.

8+ can't-miss Houston business and innovation events in April

where to be

Editor’s note: Houston's weeklong innovation festival kicks off April, followed by Rice University's globally recognized pitch competition returning for its 26th year. Plus, find coworking pop-ups, industry meetups, pitch battles and even a crawfish boil on the calendar. Here’s what not to miss and how to register. Please note: this article might be updated to add more events.

March 30-April 4 — H-Town Roundup

Celebrate innovation, entrepreneurship and collaboration at Houston Exponential's sixth-annual H-Town Roundup. During the free event series, previously known as Houston Tech Rodeo, attendees can expect insightful talks, workshops and networking events at venues across the city.

This event began March 30. Register here.

April 2 — Industrious Coworking Day

Enjoy a complimentary day of cowering at Industrious and network with professionals at the Ion. Breakfast, snacks, wifi and workspace tours are included. Following the cowering day, Industrious will host happy hour at Second Draught from 4-6 p.m.

This event is Thursday, April 2, from 8:30 a.m.-5 p.m. at the Ion. Register here.

April 2 — Technology Summit for Women

The fourth annual Women in Tech Cummil will feature speakers across three core tracks: Transformation + Digital strategy, Cyber + Risk + Resilience, and AI in Practice. Pearl Chu, director of technical domains and university relations at SLB, will give the opening remarks. Other panelists come from CenterPoint Energy, BP, Technip Energies and other leading companies.

This event is Thursday, April 2, from 2-5 p.m. at the Ion. Register here.

April 8 — Veterans Business Battle

Hear pitches from veterans and entrepreneurs as they compete for more than $10 million in investments at Rice Businesses' 12th annual Veterans Business Battle. This year, the two-day event will also feature a Small Business Expo, which invites Houston-based, veteran-owned businesses to participate in education, networking and the opportunity to showcase their business. Moonshots Capital and Mercury Fund will also host a fireside chat.

This event begins Wednesday, April 8, at 11 a.m. at the Ion. Click here to register.

April 9-11 — Rice Business Plan Competition

The Rice Alliance for Technology and Entrepreneurship will host the 26th annual Rice Business Plan Competition this month. Forty-two student-led teams from around the world, including one team from Rice, will present their plans before more than 300 angel, venture capital, and corporate investors to compete for more than $1 million in prizes.

This event begins Thursday, April 9. Find more information here.

April 10 — BioHouston Chili Cookoff

Connect with Houston's life sciences community at BioHouston's 21st annual chili cookout. This event is geared toward startup founders, researchers and industry veterans alike.

This event is Friday, April 10, from noon-4 p.m. at Bayou City Event Center. Register here.

April 14 — Mercury Fund Day at the Ion: Agentic Commerce

Don’t miss the latest installment of Mercury Fund Day at the Ion, previously known as Software Day. The recurring monthly event features office hours (by application), a keynote and networking opportunities. This month's topic focuses on agentic commerce.

This event is Tuesday, April 14, from 3:30-7 p.m. at the Ion. Register here.

April 19 – UH Energy Industry Crawfish Boil

Head to the UH Cullen College of Engineering Green Space for the 35th annual UH Energy Industry Crawfish Boil. The event will include a student showcase, STEM activities, a kids zone, live music, networking and, of course, crawfish. Proceeds from the event will support the multidisciplinary capstone fund that aims to increase professional readiness for Cullen College engineering and technology students.

This event is Sunday, April 19, from 1-5 p.m. at the Cullen College of Engineering Green Space. Find more information here.

April 24 — Rice Business Healthcare Conference

Leading experts, innovators and the next generation of healthcare leaders will converge at the Rice Business Healthcare Conference. Hosted by the Rice Business Healthcare Association, the conference will explore AI's potential impact on the sector.

This event is Friday, April 24, from 8 a.m.-2 p.m. at McNair Hall on Rice University's campus. Find more information here.

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