Ex aequo et bono (Latin: "according to what is fair and good") describes an arbitration mandate in which arbitrators are authorised by the parties to decide the dispute on the basis of equity and fairness rather than strict application of legal rules. It is one of the most flexible dispute resolution frameworks and is sometimes chosen for financial valuation disputes where rigid legal rules would produce commercially unreasonable outcomes. Ex aequo et bono arbitration is explicitly recognised under major institutional arbitration rules (UNCITRAL, ICC) when the parties expressly agree to confer this power on the tribunal.

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Example: in a shareholder dispute over the buyout price of a 30% stake in a Franco-Swiss holding company, the parties agree to ex aequo et bono arbitration. The sole arbitrator — an independent financial expert — determines a value of CHF 6.8 million by weighting three methodologies and accounting for the specific exit circumstances, shareholder relations and market conditions — a nuanced outcome that strict legal application of a single mandated method could not have produced.

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Hectelion experts are qualified to intervene in ex aequo et bono proceedings, combining technical rigour with economic equity to reach defensible and commercially sound conclusions.