How Vault.Bank achieved zero material fraud losses at account opening with Sardine
Vault.Bank is a three-year-old digital community bank based in Brodhead, Wisconsin. The bank wanted to grow its customer base by increasing account-opening conversions, but not at the cost of its fraud posture. That tension, grow fast without loosening controls, is what sent bank leadership looking for a fraud prevention partner.
Sardine is a proud ICBA ThinkTECH Accelerator Alumni. This case study was originally published by ICBA and can be found here.
The challenge
Before Sardine, account opening at Vault.Bank ran without real-time decisioning. That left the bank exposed to synthetic identities, velocity attacks, and coordinated fraud working across onboarding and payments. All of it moved faster than manual review could follow.
Growth plans raised the stakes further. Every new account channel and every new market Vault.Bank wanted to enter widened the surface area fraud could work against. A three-year-old digital bank did not have the in-house infrastructure to build that capability from scratch.
- Velocity and identity fraud. Manual review could not flag synthetic identities or coordinated attempts quickly enough to stop them before an account opened.
- Blind spots at the record level. When fraudsters started rotating through a set of email addresses to get past existing blocks, the bank's controls were built to screen individual fields rather than the pattern connecting them.
Why Sardine
Vault.Bank found its partner through ICBA's ThinkTECH Accelerator, the same program Sardine had gone through as an alumnus. The shared pedigree made the introduction straightforward.
"Knowing that Sardine was a part of the ICBA ThinkTECH Accelerator made it an easy choice to move forward with them, and we have seen the results," said Omar Hamdan, Chief Experience Officer at Vault.Bank.
The solution: Real-time decisioning tuned to the bank's own risk data
Implementation ran alongside Vault.Bank's existing stack. The bank worked with Sardine and its core provider, Fiserv, and brought in Linker Finance to keep the integration clean across systems already in place.
Rather than treat the rollout as a one-time setup, Vault.Bank and Sardine built a standing cadence: regular meetings to review fraud trends, retune rules, and reset thresholds against real account-opening data. That cadence let the bank test and ship changes without disrupting the experience of opening an account.
The rotating email addresses were one such case. Hamdan flagged the pattern to the Sardine team, who traced it to specific attributes tied to the individual applicant record rather than the address field itself. Sardine then extended the bank's rule set to block on that pattern. That closed the gap the fraud attempt had been exploiting.
The fix drew on Sardine's broader data network. "Sardine equips institutions of all sizes with the same access to behavioral intelligence, consortium data, and real-time decisioning, empowering community banks with the same solutions as top 20 banks," said Gianna Lussier, strategic account manager at Sardine.
The results: Fraud controls that hold, growth that doesn't stall
Since implementation, Vault.Bank has tracked improvement across both fraud posture and the customer experience of getting an account open.
- Fraud exposure: Zero material fraud losses tied to account opening since Sardine went live, alongside identification and blockage of high-risk applications well into the double-digit percentage range.
- Approval quality: Onboarding approval rates have improved while risk controls held steady. More of the right customers get approved, without a corresponding rise in exposure.
- Operational load: Manual review dropped, and decisioning at account opening now runs near real time, a shift from the largely manual process the bank relied on before.
- Room to grow: Vault.Bank has more confidence to expand into new markets without a proportional increase in fraud exposure.
"We can confidently say that Sardine has played a critical role in significantly reducing account-opening fraud exposure. While no system can claim zero risk in absolute terms, our current posture is the strongest it has been, and we've seen no material fraud losses tied to account opening since implementation."
Looking ahead
Vault.Bank plans to keep leaning on that cadence with Sardine as it expands into new markets, using the same real-time decisioning and rule-tuning process to hold its risk posture steady as the customer base grows.
"The Sardine team is responsive, proactive, and willing to get into the details with us. They've taken the time to understand how we operate and what we're trying to build, which makes a big difference. It doesn't feel like a one-size-fits-all solution, it feels tailored to our growth strategy."