[Case 01]
StoneClub - Rewards Program
De-risked a paid rewards model before launch. The concept test showed it wasn't different enough to charge for
- 39% flat interest, 58% competitive overlap.
[Industry]
Fintech
[My Role]
Product Designer
Context
At Stone, a Brazilian fintech built for small and mid-sized businesses, the goal was to increase adoption and retention across Card and Reserve through a paid benefits program.
The bet was that a subscription-based rewards model - cashback, higher yield on balances, and fee waivers - would drive recurring engagement and cut churn.
Problem
The model assumed customers would pay for something they couldn't get anywhere else. Early signals suggested that thing might not exist.
Before we built anything, four unknowns needed validation:
Real willingness to pay, beyond surface interest
How much of the benefit already existed in competitor offers
Whether eligibility rules would hold at scale
Whether customers could actually hit the waiver thresholds every month
What I Did
Led the concept test with n=1,514
Ran 10+ usability sessions
Analyzed eligibility constraints with the business team
Mapped the competitive benefit landscape
Defined an MVP-ready cohort of 218K customers
Structured the segmentation logic for experimentation
Outcome
The concept test (n=1,514) showed the model had low structural differentiation in a saturated cashback market:
39% expressed flat interest across pricing tiers
58% competitive benefit overlap
Limited behavioral feasibility to sustain fee-waiver thresholds
This broke the business case before we spent anything on build. My findings led the team to deprioritize the model in favor of a Visa cashback campaign with faster acquisition payback.
Business impact
Prevented investment in a subscription model that couldn't defend its price
Reduced fee-sensitivity churn risk
Avoided cannibalizing the existing cashback offer
Reused the insights to shape later credit bets
What I Learned
Customers cared about predictability more than perks. If they couldn't count on the benefit every month, a longer list of features didn't make the program feel more valuable.
The subscription only felt worth paying for when the fee waiver felt guaranteed. The moment it looked conditional, people backed off.
Uncertainty killed the perceived value, even for cashback-heavy users who should have been the easiest to win over.
In a crowded cashback market, one more benefit changed almost nothing. What people responded to was clarity: one benefit they could understand and rely on.
