How FiveBy Helped 24 Hour Fitness Cut Card Testing Fraud by 60% in 30 Days

In summer 2024, 24 Hour Fitness faced a serious threat: card testing fraud. Fraudsters used stolen card data to flood the system with rapid, low-value transactions. Between June and mid-August, 27.7% of all transactions were fraudulent. The situation peaked in early August, when the surge in fraudulent activity caused the bank acceptance rate to drop sharply to just 4.5%.

The Turning Point: A Strategic Fraud Defense

To counter the attack, 24 Hour Fitness implemented a machine learning–based fraud detection platform and partnered with FiveBy for expert fraud management. This strategic move enabled:

Real-time detection and mitigation of fraudulent activity

Adaptive decisioning that evolved with attacker behavior

Behavioral signal analysis to proactively block suspicious transactions

Within just four days of FiveBy’s involvement, the system stabilized at a new steady state—blocking approximately 72% of fraudulent transactions—marking a decisive shift in the fight against card testing fraud.

“We’ve dramatically reduced the card testing threat and saved on processing fees. With continued support, we expect even greater improvements in fraud prevention and acceptance rates.”
— Vice President of Treasury, 24 Hour Fitness

60%

Fraud Reduction

Card testing declined from 27.7% to 10.6% in just 30 days

82.5%

Bank Acceptance

Improved from 72.6%, restoring processor trust

4

Days to Stabilize

System reached new steady state within just four days

The Takeaway: Fraud Moves Fast — But So Can You

This case highlights how a strategic blend of technology and expert services can deliver fast, measurable results, even in the face of a large-scale fraud attack. With FiveBy’s support, 24 Hour Fitness not only stopped the bleeding but built a stronger, more adaptive fraud defense for the future.