Upstream
Dimitris Maniatis

Dimitris Maniatis

Chief Executive Officer

Dimitris is Upstream’s Chief Executive Officer responsible for further expanding Upstream’s growth by leading its new innovative products to market. He joined Upstream in 2017 to head Secure-D. Under his leadership Secure-D has grown into an award-winning, carrier-grade security platform, trusted by 30 mobile network operators in emerging markets. Before joining Upstream, Dimitris was in advertising through ‘all things web’, the digital marketing agency he founded in 2009. In 2014 ‘all things web’ became part of IPG and was relaunched as Reprise Digital Greece, member of the global digital marketing agency network of IPG. Dimitris holds a degree in Software Engineering, from the University of Manchester, in the UK.
Kostas Kastanis

Kostas Kastanis

Deputy Chief Executive Officer

Kostas is Deputy Chief Executive Officer, leading the strategic development and deployment of Upstream’s product stack with a view to expanding their footprint. He joined Upstream in 2015, initially as Head of Strategy and later as Head of Zero-D, the company’s pioneering ad-funded free mobile internet platform, leading it to an addressable market of 250 million people. Prior to joining Upstream, Kostas spent 8 years with McKinsey & Company, consulting banking, telco and tech companies in Europe, Africa and Asia. He spent another 3 years with MasterCard, driving business development for Mobile Wallets in SE Europe. Kostas is a graduate of the Athens University of Economics & Business in Operations Research, holds a Master’s of Science degree in Decision Sciences from the same university as well as an MBA from INSEAD.
George Kalyvas

George Kalyvas

Chief Operating Officer

George joined Upstream in 2009 and now leads the company’s largest in population department, as Chief Operating Officer. He has built a versatile profile over the years, serving from project and account management roles to being Head of Product of the company for 3 years. George is now overseeing the company’s commercial and technical operations, globally.
He is an Engineer by education, a holder of Bachelor’s and Master’s degree in Computer Engineering from the National Technical University in Athens, and an MBA holder from Cass Business School, City University, London.
Fernando Bortman

Fernando Bortman

Chief Business Officer

Fernando is Upstream’s Chief Business Officer, joining the team in December 2020. He supervises the acceleration and expansion of Upstream’s business activities across new and existing markets. Fernando possesses an extensive track record of scaling up global companies in the Telecom, Mobile Advertising and Cyber Intelligence industries.
Previously, he was VP of Sales and General Manager of the Americas Division at Verint Cyber Intelligence. He has also been General Manager at Celltick, as well as Vice President and Customer Business Executive at AMDOCS, heading the Caribbean, Latin American and European regions. He holds a Bachelor’s degree in Business Administration from the Ruppin Academic Center in Israel and speaks four languages.
Natalia Mila

Natalia Mila

Chief Technology Officer

Natalia joined Upstream in 2008 as a senior software engineer. She has worked in several roles within the company, as a team leader and later on as chief architect and head of engineering, leading the design and implementation of Upstream’s mobile commerce platform. She is now the company CTO, responsible for its technical product, engineering and infrastructure functions.
She has more than 17 years of work experience in enterprise software, in companies such as Intracom and Intralot S.A. She holds a Bachelor’s degree in Computer Science from the National and Kapodistrian University of Athens, and a Master’s degree in Distributed and Multimedia Information Systems, from Heriot-Watt University, Edinburgh.
Chrysa Karamanidi

Chrysa Karamanidi

Chief Innovation Officer

Chrysa Karamanidi joined Upstream in 2009 and soon progressed to leadership roles heading the company’s Performance Marketing, Digital Marketing and Latin America Operations divisions. In 2018 Chrysa was tasked with the development, growth and introduction to market of Upstream’s omnichannel vision, One-D, a marketing platform for accelerating digital services adoption, post-paid base growth, ARPU increase and churn reduction for mobile operators. As of beginning of 2020 Chrysa is Upstream’s Chief Innovation Officer aligning R&D and product portfolio development and roadmap with business strategy and growth targets. She holds a bachelor’s degree in Management Science and Technology from the Athens University of Economics and Business, as well as a Master of Science in Marketing from the University of Bath.
George Serfiotis

George Serfiotis

Chief Financial Officer

George has assumed the role of Upstream’s CFO in January 2021, after serving the company as Head of Financial Planning & Analysis and Deputy CFO for a total of five years. The Finance, Business Planning, Legal and Human Resources departments fall under his supervision, while he is also responsible for handling investor relations. Before joining Upstream, George spent four years working as a consulting manager at PwC in Athens. He is a Chartered Accountant (FCA) and has 14 years of results-focused international experience. He holds a Bachelor’s Degree in Economics from the University of La Verne and a Master of Science in Research Methodologies from the University of Surrey.