Kristel currently serves as an operating partner with Greater Sum Ventures, Stax’s control investor, guiding growth and operational strategies across its software portfolio. Before that, he served as CEO of CATALIS (formerly Government Brands), a software and integrated payments platform powering all levels and sizes of government across the U.S. and Canada. In the two decades prior, Kristel held CEO and COO leadership roles at various medical centers and health systems.

Kristel will lead in tandem with Stax’s Chief Operating Officer, Tony Di Sarli, who joined the organization last fall to improve operational efficiencies and support in scaling the fast-growing business. Di Sarli previously worked in similar roles at SureSwift Capital and Volaris Group collectively for more than ten years, driving day-to-day operational excellence.

“I’m impressed by the spirit and opportunity that exist at Stax and look forward to working with the entire team in escalating Stax’s mission to help businesses thrive,” said Kristel. “Stax is building an amazing legacy as a household name in payments, worldwide.”

As interim CEO, Kristel will focus on further scaling the organization on the heels of tremendous organic and inorganic growth. In taking over the daily responsibilities, Kristel will drive Stax’s focus to eliminate transactional friction between businesses and the customers they serve.

“John is a trusted partner and well-respected leader with extensive knowledge of software and payments, and we’re pleased to leverage his expertise during this exciting time in the company’s history,” said Ross Croley, founder and CEO of Greater Sum Ventures. “As Stax evolves through new roles, talent, and technologies, we’re eager to see it continue to shape the future of payments.”

Under Madhani and Rehmetullah’s leadership, Stax has grown to processing over $30 billion in payments and serving more than 30,000 businesses across the nation. Notably, Stax has led pioneering subscription-based pricing, developed the first omni-channel payments platform for card-present and not-present solutions, and launched API and Connect divisions. Most recently, Stax has made industry acquisitions including Payment Depot, Fusebill (now Stax Bill) and CardX, and secured a $245 million funding round last spring.

“We couldn’t be more proud of the success and accomplishments of the last decade with Stax, and we’ll continue to follow the Stax journey with great interest and enthusiasm,” said Madhani. “We’ll continue to support Stax into the future and are excited for our own next chapter.”

Rehmetullah added: “We’re so proud of the company we’ve built, the team we’re leaving it with, and the bright future ahead for Stax. It’s been an amazing experience to create something so special and disruptive, a business model that is truly revolutionizing the payments industry.”

In addition to Kristel, Stax has appointed additional members to the executive team, including:

Karim Noorali, Chief Risk Officer, comes to Stax from PayPal, where he worked for nearly 18 years supporting risk management and strategy. Noorali sees his role as taking on and managing risk, enabling customer growth, and helping own the end-to-end transaction.

Jonathan Razi, Chief Product Officer, was previously CEO of CardX, a surcharging automation company that Stax acquired in November 2021. With 10 years of experience in the payments and surcharging space, Razi will lead product roadmaps and innovation at Stax. CardX will continue to be one of Stax’s key product offerings.

Adam Gray, Chief Integration Officer, will be focused on navigating M&A integrations and ensuring smooth transitions for successful acquisitions. Gray joins Stax after serving in the VP role across business transformation, client success and corporate development at Abrigo, leading over 100 M&A integrations in his professional career to date.