Meet our Leadership Team and Board of Directors

Dennis Monner has served as Chief Executive Officer of Open Systems since October 2025, leading the company into its next phase of growth. As a serial entrepreneur, tech visionary, and internationally experienced CEO, he brings more than 25 years of leadership expertise in cybersecurity, cloud, and software-as-a-service.

With Gateprotect, he built one of the first German cybersecurity vendors to be recognized in the Gartner Magic Quadrant. He later founded Secucloud, which he successfully exited to Aryaka Networks. Following the acquisition, he joined Aryaka as Chief Commercial Officer. Under his leadership, the company expanded internationally and established itself as a relevant player in the SASE/XDR market.

Dennis has scaled multiple companies as CEO, CRO, and CCO across different growth stages - everything from ARR $100-250M to $0-30M and in between. He excels at combining technological excellence with entrepreneurial execution. He knows how to win in complex markets, scale global business models, and consistently put customer value at the center. His leadership style is defined by clarity, speed, and a relentless focus on empowering high-performing teams to drive growth and customer experience.

Beyond his role as CEO, Dennis is also an active investor and mentor in the European tech ecosystem. He brings extensive experience from working with private equity and venture capital firms and supports founders and executive teams in building internationally successful businesses.

Bernhard Ortner has served as Chief Financial Officer of Open Systems since 2023, after joining the company in 2021 as Director Global Finance & Accounting. He is responsible for the group's financial governance, reporting, and operational finance, ensuring transparency, stability, and scalability as Open Systems continues to grow internationally.

With a strong background in finance, accounting, and audit, Bernhard brings a disciplined and pragmatic approach to financial leadership. Before joining Open Systems, he held senior finance roles in both listed and private equity backed companies in international environments. Earlier in his career, he worked as an auditor at KPMG.

Bernhard focuses on building robust financial structures that support sound decision-making and long-term value creation. His leadership style is defined by reliability, clarity, and a strong sense of responsibility, providing a solid financial foundation for the company's strategic and operational ambitions.

Markus Ehrenmann has served as Chief Technology Officer of Open Systems since January 2023. He is responsible for ensuring that the company's SASE services operate reliably across appliance-based and cloud environments, with a strong focus on platform stability, scalability, and operational excellence.

With more than 25 years of experience in platforms, cloud infrastructure, and data-driven systems, Markus brings deep technical expertise combined with a pragmatic business mindset. Before joining Open Systems, he held senior architecture roles at Swisscom, where he contributed to large-scale data, analytics, and AI platforms, and later worked in startup environments building customer-centric data products. He has a PhD in AI and closely follows the field.

Markus is known for his ability to translate complex technology into robust, scalable solutions that deliver tangible value. He leads teams through technological change with clarity and focus, ensuring innovation is aligned with real operational needs and long-term reliability.

At Open Systems, his leadership is defined by architectural clarity and a strong commitment to dependable, high-performing platforms, supporting the continued evolution of secure, cloud-based SASE services.

Rob Swinand serves as Chief Revenue Officer at Open Systems, where he leads the company's global go-to-market strategy across sales, business development, partnerships, and revenue growth. With more than 15 years of leadership experience in enterprise networking, connectivity, and cybersecurity, Rob is dedicated to building high-performing organizations that help customers achieve measurable business outcomes.

Throughout his career, Rob has built and transformed successful sales organizations for leading technology companies. Prior to joining Open Systems, he spent more than four years as Vice President at Aryaka Networks, where he built the company's enterprise sales organization, recruited and developed high-performing teams, and helped shape its go-to-market strategy. His deep understanding of the SASE market, enterprise networking, and customer needs makes him a natural fit to accelerate Open Systems' next phase of growth. Most recently, as Vice President of Sales at HCL Software, he led the turnaround of the Americas business, rebuilding the organization and driving growth through strategic enterprise wins. Rob began his career at AT&T, where he earned multiple Diamond Club awards for delivering exceptional results with the company's largest enterprise customers.

Rob's leadership philosophy is built on collaboration, accountability, and customer success. He believes sustainable growth is achieved by empowering talented teams, fostering a culture of shared ownership, and aligning every customer engagement with long-term business value. His focus on developing people and building trusted partnerships continues to drive Open Systems' growth and customer success.

Sefki Demir serves as Vice President of Sales DACH at Open Systems, where he leads the regional go-to-market strategy and drives business development across Germany, Austria, and Switzerland. With extensive leadership expertise in cybersecurity, cloud infrastructure, and enterprise sales, Sefki is dedicated to helping organizations build resilient, secure, and future-proof connectivity networks.

Throughout his career, Sefki has established a proven track record of scaling high-performing sales operations and delivering sustainable revenue growth in highly competitive markets. Prior to joining Open Systems, he held key leadership and senior sales positions at industry-leading technology vendors, including NetApp, Fortinet, and Aryaka Networks. His deep understanding of the DACH market allows him to translate complex technological innovations into tangible business value for enterprise clients.

Sefki's leadership style is defined by a customer-first mindset, absolute clarity, and a strong commitment to execution. He believes that long-term partnerships are built on trust and shared goals, empowering his teams to deliver exceptional experiences that support clients through every stage of their digital transformation.

As Business Unit Leader for Manufacturing in Switzerland and Austria, Cécile Lüssi drives innovation and impact for customers across the region. With a clear focus on responsibility and measurable outcomes, Cécile champions solutions that empower manufacturers to thrive in a rapidly evolving digital landscape. Her approach combines strategic vision with a relentless commitment to customer success, ensuring every engagement delivers real value and strengthens long-term partnerships.

Bringing deep expertise in cybersecurity and operational excellence, Cécile shapes initiatives that anticipate industry challenges and turn them into opportunities. Her leadership reflects what Open Systems stands for: trust, transformation, and a customer-first mindset. With international leadership experience and advanced studies in digital transformation, she helps organizations navigate complexity with confidence, creating tangible benefits for clients, partners, and the broader ecosystem.

Steve Mathis is Chief Customer Officer at Open Systems, where he shapes a customer experience built on clarity, trust, and real-world results. With more than two decades in networking, security, and customer success, he brings a pragmatic, no-nonsense approach to solving complex challenges for global enterprises. His focus: making things work reliably, simply, and at scale.

Steve drives a culture where customer success is everyone's job. By uniting customer success, key account management, service delivery, and operations, he ensures that technology and service execution feel seamless for customers. He believes strong partnerships are built on transparency, shared goals, and empowering customers to move forward with confidence.

In addition to his CCO role, Steve leads the Business Unit Manufacturing & Chemicals DE/UK. His deep experience with industrial and multinational clients allows him to translate their operational realities into effective, outcome-driven solutions. He is known for connecting strategy with execution - and for teams that deliver with purpose, discipline, and a clear focus on customer impact.

Helena Grimm serves as Chief Human Resources Officer at Open Systems, where she champions people as the company's most valuable asset. She leads the organization's people strategy during an important period of organizational evolution, drawing on her strong background in talent acquisition, employer branding, and HR operations to build high-performing teams and foster a culture where individuals and the business can thrive.

Helena has been with Open Systems since 2018, holding key HR roles including Senior Talent Partner and Talent Acquisition Manager, where she played a central role in shaping recruitment strategies and strengthening the employer value proposition. Prior to this, she gained broad HR experience in both corporate and agency environments across multiple industries, leading hiring initiatives and talent programmes.

Her HR career is marked by a genuine, people-first approach, with a focus on transparent communication, strong candidate experience, and practical solutions that support both employees and the business. Helena is known for her approachable leadership style, honesty, and collaborative mindset.

Based in Zürich, she holds multiple academic qualifications and speaks several languages, enriching her ability to partner across global teams and cultures.

As General Counsel of Open Systems, Thasanee Patklom leads the company's Legal, Compliance, and Information Security functions across the Open Systems Group. Since joining the company in 2020 as its first in-house lawyer, she has built the legal department from the ground up and, in 2023, expanded her remit to include Compliance, Security and Risk, creating an integrated governance framework that supports the company's global growth.

Thasanee ensures that Open Systems operates with clarity, integrity, and long-term stability, even in complex global environments. Before joining Open Systems, she served as General Counsel and Group Data Protection Officer at Zühlke Engineering AG, where she built the legal function and implemented GDPR across the international group.

She holds a lic. iur. from the University of Basel, an LL.M., and an Executive MBA in Digital Transformation, both from the University of Zurich.

Thasanee's leadership is shaped by precision, transparency, and a forward-looking mindset. She focuses on creating frameworks that accelerate decision-making, reduce risk, and enhance customer value, ensuring that governance not only protects the company, but actively empowers teams and strengthens the customer experience.

Stefan Keller is a Senior Fellow at Open Systems, having previously served as the company's Chief Product Officer. In that role he led the strategic evolution of the SASE portfolio with a clear focus on impact, responsibility, and customer value, shaping how security, networking, and managed services come together as an integrated platform designed to operate reliably in complex, real-world environments.

He helped advance Open Systems' transition toward cloud-delivered SASE models, drawing on long-standing experience across SD-WAN, Zero Trust, ZTNA, and managed security. His work was defined by translating technological developments into practical, scalable solutions that customers can operate with confidence.

As a product leader, Stefan stood for clarity, accountability, and sustainable product decisions, emphasizing platform thinking, service-oriented architectures, and close customer proximity so that innovation delivers tangible value in daily operations.

With a strong European foundation and an international perspective, Stefan continues to support Open Systems as a Senior Fellow, contributing his experience to the company's ongoing development as a trusted SASE and managed security partner, with a focus on substance, long-term differentiation, and trust.

Daniel Gerber joined Swiss Post in 2016 as head of innovation. Since 2021 he leads Corporate Development and the Business Unit Digital Enabling Services of Post (CH) Communication Ltd. Daniel is also chairman of Swiss Post Cybersecurity Ltd.

Prior to joining Swiss Post, Daniel worked at Swisscom in strategy, business and innovation roles in Bern, Zurich and USA and Credit Suisse in Bern.

Daniel holds a Master's degree in Business Administration from the Universities Bern and Rochester, USA.

Annina Bernath has many years of management experience in various Swiss Post financial functions. As a personal employee of the CEO, she has also helped shape Swiss Post's strategy development and operating model. Today, as Co-CFO and Member of the Executive Board of Communication Services and Executive Board of the Finance function, she is responsible for the financial management of the business unit. She is also a member of various Boards of Directors at subsidiaries of Communication Services.

Nicole Burth has been head of the Communication Services business unit at Swiss Post since January 2021. This new division is about interactions between diverse stakeholders - simple, secure, digital. She previously held various management positions at the Adecco Group, most recently as CEO of the Swiss unit and as zone manager for Belgium, Luxembourg and Austria. In addition to her leadership and management experience, she has a strong track record in partnerships, mergers and acquisitions, and business development and expansion. Nicole Burth holds a Master of Business Administration from the University of Zurich and is a Chartered Financial Analyst.

Wolfgang Eger is CIO at Swiss Post since 2019 and Member of Executive Management since 2022.

Over the past 15 years, he has worked in various management positions at Swisscom and other companies such as Lufthansa, Electronic Data Systems (EDS) and McKinsey.

He's a qualified IT specialist and completed the McKinsey's MBA program in Williamstown, USA, as well as the Leadership & Organizational Change course at Harvard Business School in Boston, USA.