Jag Duggal on Building Fanatical Customers, the Sean Ellis Score, and Nubank's Product Strategy

Jag Duggal on Building Fanatical Customers, the Sean Ellis Score, and Nubank's Product Strategy

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Jag Duggal on Building Fanatical Customers, the Sean Ellis Score, and Nubank’s Product Strategy

Source: Lenny’s Podcast Speaker: Jag Duggal Link: Episode

Overview

Jag Duggal is CPO of Nubank, the Latin American neobank with 90+ million customers across Brazil, Mexico, and Colombia — bigger than Coinbase, Robinhood, Affirm, SoFi, and Lemonade combined, with 80–90% of growth driven by word of mouth. He joined from Facebook, where he ran video monetisation, and before that led display advertising strategy at Google.

The episode covers how Nubank operationalises “we want our customers to love us fanatically” as a concrete product development discipline: the Sean Ellis score as a hard PMF gate before scaling, the bullseye cohort methodology for iterating products to love, and a clear-eyed view of strategy as concentrated bets — not hedging, not incremental improvement, but fundamentally different experiences.

Key ideas

  • Fanatical customer love as North Star. Nubank’s first of five cultural values is “we want our customers to love us fanatically.” This isn’t a wall poster — it is the active decision-making filter when trade-offs arise. Every product review asks: will this make customers love us enough to tell their friends?
  • Sean Ellis score as PMF gate. Nubank does not scale a product until at least 50% of customers say they would be “very disappointed” if it went away — adjusted up from Sean Ellis’s 40% threshold to account for Brazilian cultural optimism. Product managers are culturally expected to say no to scaling until the gate is met.
  • Bullseye cohort methodology. When the overall Sean Ellis score is borderline, find the small segment that scores 70%+ and reverse-engineer what they share: how many products registered, which payment rails active, etc. That bullseye segment reveals what “great” looks like; the job is then to expand the bullseye. Illustrated with the Payments Assistant product going from hundreds of thousands to 10 million monthly actives by identifying users with 4+ commitments across 2+ rails.
  • Fundamentally different, not incrementally better. Nubank’s operating mantra. Only a fundamentally different experience compels word-of-mouth growth; incremental improvement does not. This applies at product level and company level: the neobank category was defined by branchless, digital, zero-fee credit in a market where incumbents were profitable and hated.
  • Strategy is concentrated bets. Quoting Rumelt’s Good Strategy Bad Strategy: strategy is a coherent plan to apply your strengths in a leveraged way against a specific problem — not a broad aspiration, not a set of financial goals. Diversification preserves wealth; concentration builds it. Hedging produces diffuse execution and unreadable results.

Frameworks

Sean Ellis score implementation at Nubank:

  • Survey question: “How disappointed would you be if this product went away?” (Very / Somewhat / Not disappointed)
  • Standard threshold: 40% “very disappointed” (Sean Ellis original)
  • Nubank threshold: 50% (adjusted for Brazilian cultural politeness/optimism)
  • Applied before scaling any product, at each iterative stage
  • Combine with direct phone calls to 10 customers; five calls usually reveals the pattern

Nubank’s five cultural values:

  1. We want our customers to love us fanatically
  2. We are hungry and we challenge the status quo
  3. We build strong and diverse teams
  4. We pursue smart efficiency
  5. We think and act like owners, not renters

Strategy synthesis (across Rumelt, Roger Martin, and Nubank practice):

  • A strategy is not: an ambitious goal, an aspiration, financial targets
  • A strategy is: a coherent plan for applying specific strengths against a specific important problem, for a specific customer
  • Kevin Systrom (Instagram): “We may not be right, but at least we are clear”