Bad Blood: Secrets and Lies in a Silicon Valley Startup

Reviewed by Diario de un Inversor · UpdatedJuly 8, 2026

Our review

John Carreyrou was a Wall Street Journal reporter when he began investigating Theranos, the blood-testing company founded by Elizabeth Holmes that reached a nine-billion-dollar valuation with technology that never worked. His articles began appearing in late 2015 under considerable legal pressure, and this book is the full reconstruction of the case. What makes it required reading for anyone analysing companies is not the fraud story but the catalogue of signals the environment chose to ignore. Theranos had a board full of former secretaries of state and generals, and not one expert in clinical diagnostics. It churned executives and technical staff at an anomalous rate. It never submitted its device to independent validation nor published in peer-reviewed journals. And each funding round closed at a higher valuation without any of those questions being answered. Carreyrou narrates soberly, without underlining, and lets the accumulation of facts do the work. Beyond being fine journalism, it is a practical exercise in due diligence.

Key takeaways

• A prestigious board without technical competence validates nothing.
• The absence of independent validation and peer-reviewed publication was the decisive signal.
• Anomalous churn among technical staff frequently precedes discovery of the problem.
• Each funding round raised the valuation without answering the outstanding questions.

Fact

Winner of the 2018 Financial Times and McKinsey Business Book of the Year; the Spanish edition is published by Capitán Swing, translated by Begoña Valle Simón.