What factors are contributing to the sudden increase in declined transactions for Marqeta's virtual card issuance API in the last week?

Introduction

The sudden increase in declined transactions for Marqeta's virtual card issuance API in the last week is a critical issue that demands immediate attention. This problem directly impacts our core service offering and could have significant repercussions on customer satisfaction, revenue, and market position. I'll approach this analysis systematically, focusing on identifying the root cause, validating hypotheses, and developing both short-term fixes and long-term solutions.

Step 1

Clarifying Questions (3 minutes)

• Given the abrupt nature of the increase, I'm wondering about recent changes. Have there been any updates to the API or related systems in the past two weeks?

Why it matters: Recent changes often correlate with sudden performance shifts. Expected answer: Yes, a minor update was pushed last week. Impact on approach: If confirmed, I'd prioritize investigating that update.

• Considering the scope, I'm curious about the extent of the issue. What percentage increase in declined transactions are we seeing compared to our baseline?

Why it matters: The magnitude helps prioritize the response and resources needed. Expected answer: A 30% increase in declined transactions. Impact on approach: A larger increase would suggest a more systemic issue.

• Thinking about user segments, I'm wondering if this affects all users equally. Are we seeing any patterns in terms of user types, transaction amounts, or merchant categories?

Why it matters: Segmentation can reveal targeted issues vs. system-wide problems. Expected answer: Higher decline rates for transactions over $1000 and in certain merchant categories. Impact on approach: This would narrow our focus to specific transaction types or user segments.

• Reflecting on external factors, has there been any change in our fraud detection algorithms or third-party services we rely on?

Why it matters: External dependencies can significantly impact our service performance. Expected answer: No changes to fraud detection, but a new third-party service was integrated recently. Impact on approach: This would shift focus to the integration and performance of the new service.