Reinsurance sidecar market estimated at record $23bn in 2026: Aon Securities

The outstanding market for collateralized reinsurance sidecar structures has reached a new record high of $23 billion in 2026, representing roughly 50% growth since the end of 2024, according to estimates from Aon Securities.

Aon Securities has been tracking the expansion of the reinsurance sidecar market over recent years.

Data from the company showed that outstanding reinsurance sidecar capital had reached $10 billion at the middle of 2024.

The reinsurance sidecar market then increased by a staggering 70%, reaching a new record high of $17 billion by the end of June 30th 2025.

Momentum continued to follow in the back half of 2025. By September 30th, 2025, Aon estimated that the sidecar segment managed to grow its invested capital base a further 15% in the third quarter alone, reaching $19.6 billion.

This total also consisted of a property sidecar market at $17.9 billion of invested capital and a casualty sidecar market at around $1.7 billion

Then, earlier this year, Aon Securities team revealed that it estimated that sidecar capital had grown by more than $5 billion over the course of full-year 2025, with casualty and non-catastrophe vehicles cited as key drivers of the sidecar market’s expansion.

And now Aon’s data shows that as of the end of June 2026, the sidecar segment has managed to grow its invested capital base to a staggering $23 billion, which as mentioned, marks a 50% increase since the end of 2024.

This sharp increase has been fueled by earnings from existing sidecars as well as new vehicles primarily employing asset-driven strategies for casualty and whole-account portfolios, Aon Securities highlights in the broker’s latest ILS market report.

“Short-tailed strategies for property and specialty remain popular with clients and investors as existing relationships remain balanced in a softening market,” Aon Securities said.

The firm added: “In the asset-driven space, favorable conditions for both (re)insurers and asset managers have coincided to match issuance with strong demand. Attractive premium levels and elevated interest rates continue to underline the attractive economics for deploying third-party capital into the (re)insurance markets.

“Asset managers seeking scalable private credit investment opportunities have increasingly recognized sidecars as a meaningful foundation for insurance asset management and a source of attractive returns. For (re)insurers, sidecars offer a capital-efficient way to write more business, receive favorable commission income, and establish partnerships with high-quality asset managers.”

Further into the report, Aon Securities stated that reinsurance sidecars continue to be heavily structured around two main portfolio approaches: assumed sidecars and ceded (ReShare) sidecars.

Assumed structures are generally used to provide customised capacity, aligned partnerships, and fee income, whereas ceded structures tend to concentrate on ensuring reliable capacity and facilitating smoother execution.

Aon Securities also observed that more sponsoring entities are taking a portfolio-based approach to ceding risk rather than limiting sidecars to a single line of business. This shift ultimately allows for a wider array of risks, including specialty lines, thereby further improving diversification.

“This evolution reflects the broader maturation of the ILS market, as sidecars increasingly operate as institutional capital structures rather than tactical capacity vehicles. Aon Securities expects this trend toward greater diversification and new sponsoring entities and investor entrants to continue,” the firm concluded.

Find details of numerous reinsurance sidecar investments and transactions in our directory of collateralized reinsurance sidecars transactions.