Mario Zimmermann presents a milestone in the research on a valuation report that is often used in conjunction with transactions: the "Fairness Opinion." He clearly and distinctly outlines the multifaceted functions that have been formulated by practice. He then theoretically analyzes these functions using an innovative methodology and derives concrete recommendations for action and design for standard setters, commissioning administrative bodies, shareholders, auditors, and judges. A "Fairness Opinion" is often commissioned by executive boards or supervisory boards to avoid the accusation that the purchase or sale price was not appropriate during corporate transactions. Despite the observable high popularity of this supposed valuation report, it has so far lacked scientific examination.