Sinistralité

Sinistralité is a term used in insurance and risk management to describe the level of losses arising from insured claims relative to premiums. It is a central indicator of underwriting performance and risk profile for a portfolio of contracts. In practice, sinistralité is most often expressed as the loss ratio, or taux de sinistralité: the ratio of claims paid and handling costs to earned (or primes acquises) premiums. Depending on the context, the numerator may include indemnités versées, provisions for outstanding claims, and related claims-handling expenses, while the denominator is the earned premiums.

The concept rests on two main components: fréquence and gravité. Fréquence des sinistres refers to how many claims occur per exposure unit (policy, vehicle, or risk). Gravité des sinistres describes the average cost per claim. The overall sinistralité reflects the combined effect of these factors and is often influenced by external events, risk selection, policy terms, and portfolio composition. Reinsurance reduces the net sinistralité retained by the insurer.

In practice, sinistralité is used to guide pricing, underwriting discipline, and reserve setting, and is analyzed alongside other indicators such as the expense ratio and the combined ratio. Practitioners distinguish between sinistralité technique (claims and related costs relative to earned premiums) and overall profitability, which also includes investment results (sinistralité financière). Limitations of the metric include potential distortions from timing effects, large but infrequent claims, or changes in accounting and reserves.