AppNexus names Jonathan Hsu CFO and COO, makes major Executive Team appointments

Press Release

New York – AppNexus, the technology company that provides trading solutions and powers marketplaces for Internet advertising, today announced four substantial appointments to bolster its world-class executive team. Jonathan Hsu, who served as CEO of 24/7 Media, one of New York's most successful technology companies, and helped engineer its $649 million sale to WPP in 2007, will become CFO and COO. Geir Magnusson, Jr., who led engineering and technical operations for companies including Gilt Groupe, 10gen and others, will become CTO. Also joining AppNexus' leadership team are Casey Birtwell, who has been hired as SVP, Strategy & Operations and Michelle Dvorkin, who has been promoted to SVP, People.

"At 24/7 Media, Jon built and sold one of the biggest ad tech companies ever. He's an extraordinary talent and true industry pioneer with unique, proven experience as CEO, CFO and COO of a digital marketing business – a background that will be invaluable as we cement our place as an elite, global technology company," said Brian O'Kelley, CEO and co-founder, AppNexus. "We've grown at a remarkable rate over the last year expanding our leadership team, adding hundreds of employees worldwide and transacting more than one billion dollars through our platform. Jon, Geir, Casey and Michelle will provide a huge boost as we build on that momentum and move into our next stage of growth."

"I'm thrilled to join the unparalleled leadership team at AppNexus, which is a driving force in the ad tech industry and rapidly building one of the most relevant and distinctive technology companies in the world," said Hsu. "It's an incredibly exciting moment in the evolution of this industry, and I'm looking forward to bringing my experience leading highly successful, fast-growing companies to bear with AppNexus."

Over the course of 2013, AppNexus grew revenue significantly while transacting more than $1 billion of advertising spend across its global platform. The company raised a $75 million Series D round and hired more than 300 people over that same period of time, expanding to nearly 600 full-time employees in ten offices worldwide. Following the launch of the world's largest premium mobile ad exchange with Millennial Media in September, AppNexus has gone on to become the leading independent source for programmatic mobile supply globally, seeing more than ten billion mobile impressions daily. The company was recognized by the World Economic Forum in August as a 2014 Technology Pioneer and one of the globe's most promising new technology companies.

Hsu was most recently CEO of Recyclebank, one of Fast Company's "50 Most Innovative Companies." Before that, he spent 11 years in senior leadership positions with 24/7 Media, a company focused on the science of digital marketing, in roles that included CFO, COO and CEO. In that capacity, Hsu significantly grew the publicly-traded company's revenues and raised its equity value from $10 million to an ultimate acquisition price of $649 million, when it was purchased by WPP in 2007. Hsu also worked as an investment banker at JP Morgan.

As CTO, Magnusson will be responsible for technology strategy and product delivery at AppNexus, and will drive the evolution of the company's product architecture. In addition to his previous AppNexus experience as VP, Engineering, Magnusson carries years of knowledge as a technical executive and leader for companies including Viggle, where he served as CTO, and Gilt Groupe, where he held the role of VP, Platform and Architecture and Chief Architect.

As SVP, Strategy & Operations, Birtwell will assume the responsibility of overseeing strategic alignment at AppNexus, ensuring the business is focused on key initiatives and execution, as well as sales, contract and business operations. Birtwell comes to AppNexus from Avaya, a leading global provider of business communications systems, where he held a series of leadership roles.

In her elevated position of SVP, People, Dvorkin will manage all aspects of human resources and people matters. As she has done for the past year, Michelle will continue to work closely with senior management, developing and implementing leadership plans and strategies in furtherance of overall business goals. Her main objective is to ensure that AppNexus has the best talent in the industry by managing a competitive compensation and benefits structure, focusing on company culture and helping to implement AppNexus' core values.


AppNexus is a technology company that provides trading solutions and powers marketplaces for Internet advertising. Our open, unified, and powerful programmatic platform empowers customers to more effectively buy and sell media, allowing them to innovate, differentiate, and transform their businesses. As the world's largest independent ad tech company, AppNexus is led by the pioneers of the web's original ad exchanges. Headquartered in New York City with ten global offices, we employ hundreds of the brightest minds in advertising and technology who believe that advertising powers the Internet. For more information, follow us at @AppNexus or visit us at