Mark Grether

Mark Grether

Chief Executive Officer

Mark is the CEO of Sizmek, where he is focused on guiding the company and its leadership team and accelerating the growth of the business. Prior to Sizmek, Mark was the cofounder and global Chief Operating Officer of WPP’s Xaxis, which under his leadership grew into the largest programmatic media company in the world, with more than $1 billion in revenue in just five years. Prior to Xaxis, he was Global Development Director of GroupM, the world’s largest media investment group, where he was instrumental in setting up GroupM’s digital trading desk across 10 countries. Mark also spent time in academia, teaching at university in Germany after receiving his PhD in Marketing from the University of Mannheim, until the lure of real-world marketing data drew him onto the ever-compelling advertising technology trajectory. Since 2011, Mark has lived in New York City with his wife and two sons, who he attempts to one up at soccer each weekend—but they’ve got mad skills.

Rachel Walkden

Rachel Walkden

Chief Operating Officer

Rachel Walkden is Chief Operating Officer of Sizmek. A born productivity buff, Rachel focuses on delivering world-class service and support to Sizmek’s clients around the globe. Whether you drive the platform yourself or Sizmek does it on your behalf, Rachel leads a team of ops ninjas who partner with you every step of the way from day one. Rachel has many years of experience in digital media operations, including leading global operations at Operative, growing the services business there three-fold, and as COO for Ringleader Digital, scaling up the business more than ten-fold. When not focused on figuring out ways for Sizmek to serve its customers better, Rachel likes to be doing something adventurous and vaguely dangerous.


Sarah Goodhart

Interim Chief People Officer

As Interim Chief People Officer, Sarah Goodhart is helping Sizmek’s dynamic organization evolve while maintaining and fostering a strong team culture. Prior to Sizmek, Sarah was global head of HR for Intrasphere Technologies, LLC, a boutique technology consulting and software company. Sarah started her career as a systems consultant and migrated into human resources during her tenure with Accenture. Since then, she has enjoyed leading HR teams and creating successful teams for a number of technology consulting firms. A native New Yorker, Sarah pursues a wide range of interests in her off hours that only her hometown can provide, from taking in Broadway’s best to rooting for the Rangers to attempting—and sometimes succeeding—in creating delicate hand-blown glass art.


Eric Duerr

Chief Marketing Officer

Eric Duerr is Chief Marketing Officer at Sizmek. As the steward of the Sizmek brand, Eric oversees global communications efforts, driving Sizmek’s strategy through thought leadership, demand creation, and customer activation. Before taking the reins at Sizmek, Eric was the Chief Marketing Officer at Rocket Fuel, where he was instrumental in positioning it as one of the most recognized brands in ad tech. Prior to Rocket Fuel, Eric was the Founder and Chief Executive Officer of the multi-award-winning communications consultancy Emphatic, specializing in B2B marketing and sales motion strategy for clients that included Microsoft, Adobe, the BBC, GoDaddy, and Pitney Bowes. When he’s not working on Sizmek’s next product launch or advising clients on how to create impressions that inspire, Eric enjoys laser-slicing his lethal drop shot on the tennis court, riffing on his piano or sax, enjoying an icy-cold India Pale Ale, or pondering ways to apply timeless principles of Eastern philosophy to modern business opportunities for Sizmek’s customers around the world.

Mike Caprio

Mike Caprio

Chief Growth Officer

As Chief Growth Officer, Mike oversees Sizmek’s partnerships, business development, global holding companies, supply solutions, programmatic business unit, and Peer39.  Mike’s 20-year career spans across traditional and digital advertising, leading companies such as Disney, CBS, and Visible World, and cofounding SWMX, the first demand-side and supply-side platform for buying TV and radio.  When Mike’s not growing new business for Sizmek, you can probably find him making a mean marinara sauce for his wife and two sons down at the Jersey shore or obsessing over the latest Yankees, Giants, Knicks, or Rangers game—Mike’s a superfan and doesn’t take a season off.


Neil Coleman

General Manager, Americas

Though Irish by birth, Neil Coleman jumped across the pond by way of nine other countries to become Sizmek’s General Manager of the Americas, where he leads sales teams, publisher business, and strategic planning across North and South America. He focuses on driving revenue, building customer relationships across agencies and brands, and managing Sizmek’s overall regional presence. Prior to Sizmek, Neil held a number of senior revenue and operations leadership positions at top digital companies, including Snapchat, Google, AdRoll, and IBM. He has built and led national and international teams in the United States, Europe, Asia, and Australia. Neil’s drive for success doesn’t stop in his off hours—he coaches soccer to kids ages 7 to 77 when he’s not running marathons or taking on a fourteener in his trusty hiking boots.


David Gosen

General Manager, EMEA

David Gosen is General Manager, EMEA, where he is responsible for Sizmek’s strategy and growth across the region. Before Sizmek’s acquisition of Rocket Fuel, he ran its global SaaS platform and led the international commercial and operations teams for all markets outside the United States. Prior to Rocket Fuel, David’s positions included CEO of Nektan Plc, a publicly listed online casino business, and Managing Director of Nielsen’s digital, online, and mobile effectiveness practice. He spent more than 10 years in the video gaming industry as Managing Director of Nintendo of Europe, VP of Xbox Europe at Microsoft, and CEO of VC-backed I-play Mobile Gaming. His successes have been fueled by that life-changing moment in 1981 when he saw “The Boss” perform live—and like Springsteen, David knew that he was always “born to run.”

Kees De Jong

Kees de Jong

General Manager, APAC

As Sizmek’s General Manager of APAC, Kees de Jong oversees the growth and development of customer engagement, sales development and innovation, strategic planning, regional presence, and revenue growth in the Asia-Pacific region. Prior to Sizmek, Kees held senior management positions at Facilitate Digital (now Adslot) in Australia, and ran the company’s European operations for two years before establishing the programmatic buying capability for GroupM (now Xaxis). Most recently, he was a consultant, serving large media, tech, and data companies. When Kees isn’t digging up new business innovations, you can find him riding on a large tractor as he harvests copious amounts of garlic, ginger, and turmeric on his organic farm near Sydney.

Volker Hatz

Volker Hatz

Chief Data Officer

As Chief Data Officer, Volker Hatz oversees Sizmek’s fast-growing data business, including data governance solutions and analytics initiatives, and product marketing. Prior to joining Sizmek, Volker was Global Head of SAP XM DMP Solution at SAP Exchange Media. Throughout his career, he’s played key roles in creating groundbreaking technology to bring structure to the stores of data that digital advertising has uncovered, including the first demand-side advertising platform, the first second-party data management platform, and the first real-time cookie-less targeting. When Volker’s not driving innovation in data or spending time with his wife and four children, he’s swinging his nine iron on the golf course, aiming for that elusive hole in one.


Markus Plattner

Chief Technology Officer

As Chief Technology Officer, Markus Plattner leads innovation creation and manages Sizmek’s product engineering and IT teams. With more than 25 years of experience in designing, implementing, and operating highly scalable software solutions, Markus specializes in data management and advertising platforms, which has led him to play instrumental roles in building world-class solutions at GroupM, Xaxis, Quisma, and Eyewonder. If he’s not in Germany, where he lives with his wife, two teenage daughters, two dogs, and a cat, Markus can be found in Israel, Krakow, or New York, where he is leading creative collaborations that provide inspiring solutions for Sizmek clients. In his free time, Markus enjoys flying helicopters and playing table tennis, though usually not at the same time.