ISG Tango™

Clay Calhoun, ISG Partner and ISG Sourcing Solutions Leader, is a senior member of ISG’s Americas Leadership Team. He brings more than 25 years’ experience in IT consulting, strategy, service delivery, and advisory services. His experience includes leading, managing, and supporting Global 2000 client engagements which consider solutions that maximize the benefits from internally optimized and sourced service delivery operations. With ISG, Clay has advised on more than 50 engagements totaling more than $25B of contract value.

Karen Collyer is a director in ISG’s Digital Practice and works with our clients to optimize their IT operations and transform their organizations to align to business outcomes. She specializes in technology enablement/operational excellence programs that range from app and ERP development to website redesign to UX alignment. The firm also looks to Karen to work with our clients to manage large, multi-deliverable initiatives as well as the day-to-day relationships with a number of our high-profile clients.

LinkedIn Profile

Ant leads ISG's UK & Ireland Market.  He works with clients to navigate their most complex challenges and support them to over-achieve their goals. He is excellent at building broad relationships and driving consensus amongst a diverse range of stakeholders. He uses his experience gained working at senior levels in large enterprise clients, coupled with deep relationships with the service provider community, to drive the best possible outcome for clients. He has worked across a range of different sectors, from the top end of the FTSE100 to local government and charities.  In each case, he works to understand client imperatives, and design solutions tailored to deliver their objectives.

Dr. Daniel Gerster is a Partner at ISG and offers clients more than 22 years of experience in strategic information management, thereof nine years as global CIO in a professional services company and more than 13 years in management consulting. Daniel helps CIOs and leading IT executives to successfully master digital transformation and to increase core capabilities such as organizational agility or resilience. He has a highly successful track record in CIO advisory. He is a well-known specialist for IT sourcing and contracting and covers commercial, legal and data protection aspects. He is a recognized speaker at conferences for IT executives, on IT events such as Sapphire, DSAG, VOICE, and BME IT Sourcing, VOICE Entscheiderforum.

Prashant Kelker is Chief Strategy Officer of ISG, Partner of ISG Americas Consulting and a member of the ISG Executive Board (IEB). He was named to the IEB in January 2023. Prashant was appointed Chief Strategy Officer in 2018, responsible for developing the firm’s three-year strategic blueprint, and he was instrumental in the development of our highly successful ISG NEXT operating model in 2020.

In January 2023, he was named to the expanded role of Partner, Americas Consulting, bringing together all our advisory capabilities in the region to support our commercial and public sector clients in response to the growing convergence of digital technology and enterprise operating models, business processes and revenue-generating connected products and services.

Prashant joined ISG in 2012 from Accenture, initially working for our DACH business and based in Germany. He moved with his family to the United States in 2018. Prashant earned his MBA from the Indian Institute of Management in Bangalore and a BE in electronics from Bangalore University in India.

Kathy Rudy is Chief Data and Analytics Officer of ISG and a member of the ISG Executive Board. She was named to this post in January 2020. Kathy is responsible for the development of ISG data solutions and platforms to deliver new and even more valuable insights to our clients, as part of the overall ISG Platform strategy. She is working across the firm to enhance our data products, develop data-driven consulting assets, and increase our go-to-market effectiveness. Throughout her 20 years with the firm, Kathy has supported hundreds of client organizations as they leverage data to drive greater efficiency and effectiveness in their IT operations, build measurement programs and support critical sourcing decisions. She was responsible for the development of ISG Inform™, the firm’s next-generation data-as-a-service platform solution, launched in 2019. Before joining ISG in 2000, Kathy, a graduate of Michigan State University, was part of the Unisys team that managed the transition from internally delivered IT services to an outsourced environment for the City of Chicago.

Chuck Walker, ISG Partner and America’s Transaction and Transition Leader, leads the Sourcing Strategy group within the Sourcing Solutions team. Chuck brings more than 25 years’ experience in IT strategy, service delivery, consulting and advisory services including assessments, strategies, transactions, implementations, service management and corporate governance and compliance.