Why Banks Need ‘Sleepy’ Customers

Key Takeaways

• Only 5‑15% of depositors open new accounts each year
• Sleepy deposits represent 58% of a bank’s franchise value
• In low‑concentration markets, sleepiness raises mark‑ups and profitability
• Without sleepy customers, default risk for major banks exceeds 20%

Pulse Analysis

The concept of "sleepy" depositors—customers who rarely switch banks—has long been an under‑explored driver of banking economics. By leveraging granular account‑opening and closure data, the HBS authors reveal that depositor inertia is not random but largely driven by life events such as moves or death, rather than rate shopping. This low churn environment creates a hidden layer of market power for banks, allowing them to maintain higher spreads on deposits without aggressive competition.

The researchers translate this behavior into a dynamic "invest‑versus‑harvest" model that quantifies the value of sleepy deposits. Their estimate that 58% of a typical bank’s franchise value stems from depositor inertia underscores how critical retention is to profitability. In regions with few competitors, the effect magnifies, pushing up mark‑ups and rewarding banks with weaker service offerings or higher marginal costs. Moreover, the model links sleepiness to systemic resilience: without it, the probability of default for two leading money‑center banks would have risen above 20% after the Fed’s recent rate‑hiking cycle.

For practitioners and policymakers, these insights suggest a double‑edged sword. While banks can leverage sleepy customers to enhance earnings, regulators must monitor concentration risks that may be masked by apparent stability. Digital banking tools that lower switching frictions could erode this inertia, prompting a shift toward more competitive pricing and service innovation. Future research should explore how fintech adoption and demographic shifts might alter the sleepy‑deposit landscape, guiding both strategic bank decisions and supervisory frameworks.