Clusia Acquires Optim ACH Solutions to Scale Its AI-Native Assurance Firm

Clusia, an assurance firm for financial technology companies and banks, today announced the acquisition of Optim ACH Solutions, an ACH audit practice founded by Debbie Arai, and the appointment of Brian Stearns as…

Clusia4 November 20263 min read

The acquisition brings Optim's auditors and clients onto Clusia's assurance model. Brian Stearns joins from Wespay as Managing Director of Assurance Operations.

NEW YORK, Nov. 4, 2026 /PRNewswire/ -- Clusia, an assurance firm for financial technology companies and banks, today announced the acquisition of Optim ACH Solutions, an ACH audit practice founded by Debbie Arai, and the appointment of Brian Stearns as Managing Director of Assurance Operations. Terms of the acquisition were not disclosed.

Clusia acquires Optim ACH Solutions

Clusia delivers regulatory audits and independent testing for companies that move money, starting with ACH audits and BSA/AML testing. Its auditors lead every engagement from start to finish, while proprietary software gathers evidence from clients' uploaded documents or connected systems, reducing the work required of their teams. Clusia's auditors then review the results, investigate exceptions and apply professional judgment before signing the final report.

With the acquisition, Clusia now serves more than 60 fintechs, third-party senders and third-party service providers. Optim will continue to operate as Optim ACH, a Clusia company, and its clients will keep working with the same team.

"AI is going to increase both the volume and complexity of work that requires independent assurance, and the firms doing that work today can only sell the hours they have," said Reed Switzer, co-founder and CEO of Clusia. "We built Clusia for that demand. Bringing in Optim establishes our ACH practice and expands our client base. Our ambition is to become the assurance firm companies rely on across their most important regulatory and financial obligations."

Less work for clients, more extensive testing
Audit work often starts with clients gathering records from disconnected systems and answering lengthy questionnaires. Auditors then spend substantial time assembling and reviewing that evidence, limiting how much work a firm can take on. Clusia is built to reduce the burden on both sides. When clients connect supported systems, Clusia can test larger transaction samples than traditional manual methods allow.

"Because the software and audit practice sit under one roof, Clusia's engineers work side by side with the auditors accountable for the final report," said Nolan Hendrickson, co-founder and CTO of Clusia. "That lets us turn what auditors learn in the field into a better product. Every engagement makes the next one faster, more consistent and easier to deliver."

Experienced practitioners, supported by proprietary technology
Clusia pairs fintech operators and engineers specializing in cybersecurity and AI with seasoned audit practitioners. Brian Stearns joins after more than a decade at Wespay, most recently serving as SVP, Supervisor of Risk Management Services. At Clusia, he will lead audit delivery improvements and the expansion into additional assurance services.

Debbie Arai, Optim's founder and a veteran of payments risk management and audit, joins Clusia as Managing Director, ACH Audits.

"We've always been focused on delivering high-quality audit work for our clients," said Debbie Arai. "What's exciting about Clusia is the ability to pair that expertise with software we build ourselves – making the experience easier for clients, improving how we work year over year, and giving us the ability to support them across more of their assurance needs. Importantly, Optim clients will continue working with the same team they know and trust."

Clusia plans to bring more of each client's recurring assurance work into one relationship, with relevant evidence carrying forward between engagements. Over time, the company intends to expand from periodic audits toward continuous independent assurance.

Companies seeking an audit or a demonstration of the Clusia experience are encouraged to contact team@clusia.com.

About Clusia
Clusia is the assurance firm for financial technology companies and banks. It combines proprietary software with in-house, accredited practitioners to deliver regulatory audits and independent compliance testing with less work for clients.

About Optim ACH Solutions
Optim ACH Solutions is an ACH audit and risk assessment practice founded by Debbie Arai, an Accredited ACH Professional since 2007. Its clients are fintechs, third-party senders and third-party service providers that rely on the ACH network.

Media contact:
Reed Switzer
rs@clusia.com