Catastrophe bonds and ILS: how they work and who they affect

A catastrophe bond is a security that works as fully funded reinsurance. Investors hand over cash, which sits in a trust; if a defined disaster hits, that cash pays the insurer, state pool, government agency or company that sponsored the bond, and investors lose some or all of their principal. If no trigger event occurs, investors get their money back at maturity plus a coupon along the way. Cat bonds and the wider market for insurance-linked securities (ILS) now supply a large and growing share of the capacity behind U.S. property catastrophe risk, which is why they influence what property carriers charge you.

How the structure works

Artemis, the trade publication that tracks the market, describes the mechanics this way: a special purpose insurer enters a reinsurance agreement with the sponsor, issues securities to investors, and holds the proceeds in a collateral account typically invested in highly rated money market funds (Artemis). In sequence:

1. The sponsor (usually a ceding insurer, but also a reinsurer, a state-backed pool or a utility) decides how much catastrophe protection it wants and at what attachment point.
2. An independent modeling firm runs the sponsor's exposures through a catastrophe model and estimates the probability that investors lose principal.
3. A special purpose vehicle, commonly based offshore in a jurisdiction such as Bermuda or the Cayman Islands, issues notes to investors, often under Rule 144A, and uses the proceeds to back a reinsurance contract with the sponsor.
4. The sponsor pays a premium. Investors earn that premium (the spread) on top of the return the collateral generates.
5. If a covered event meets the trigger, collateral is released to pay the sponsor and investors absorb the loss. If not, the notes mature, commonly after three years, and principal is repaid.

Because the cash is already in the trust, the sponsor has almost no credit risk on its protection. That is the main structural difference from a traditional reinsurer, which promises to pay from its balance sheet later. Sidecars and collateralized reinsurance use the same fully funded idea in private form; see Sidecars, collateralized reinsurance and ILS funds explained.

What triggers a payout

The gap between what triggers the bond and what the sponsor actually lost is called basis risk. Indemnity structures minimize it. Artemis's third-quarter 2026 report notes that industry loss triggers dominated that quarter, with nine tranches worth $720 million, while indemnity deals made up just over 13% of issuance; indemnity usually accounts for the majority in a typical quarter (Artemis Q3 2026 report). For businesses buying coverage rather than sponsoring bonds, the same trade-offs show up in parametric insurance for businesses.

Size and pricing in 2026

The figures below come from the Artemis Q3 2026 report, which includes private deals and uses the dates stated.

• Record issuance in 2025. Cat bond issuance reached $25.6 billion in 2025, the first year above $20 billion, from a record 122 transactions.
• Another strong year in 2026. Issuance totaled $18.9 billion in the first nine months, a record for that period, from 93 transactions. Fourteen new sponsors had entered the market by the end of September.
• Outstanding market. About $65.5 billion at September 30, 2026, up 7% from the end of 2025.
• Pricing. The average spread above expected loss was 3.97% in the third quarter, and the average multiple (spread divided by expected loss) was 2.27, below 3 for a fifth quarter running. Average pricing came in 8.2% below the midpoint of initial guidance, the eighth quarter in a row of negative price change.
• Who sponsored. Third-quarter deals included Swiss Re's $345 million Matterhorn Re and Hannover Re's $200 million 3264 Re, both covering U.S. and Canada named storm and earthquake; Porch Group's first deal at $100 million; and the Los Angeles Department of Water & Power's $100 million California wildfire bond.
• Investors. UCITS cat bond funds, a European regulated fund format, held about $21.76 billion at September 30, 2026, which Artemis put at around 33% of risk capital outstanding (Artemis).

The pricing numbers matter because cat bonds compete with traditional reinsurance. When investors accept lower spreads, reinsurers have to meet the price. Guy Carpenter's U.S. Property Catastrophe Rate-on-Line Index was down about 16% through the 2026 renewals and about 22% below its 2024 peak (Artemis). The rate on line concept explains how those layer prices are measured.

Cat bonds versus traditional reinsurance

Worked example (hypothetical)

Say a regional carrier with heavy Gulf Coast commercial property exposure wants $100 million of hurricane protection above a $300 million attachment point for three years. An independent model puts the chance of losing investor principal at an expected loss of 2% a year. Investors price the notes at a spread of 6%, a multiple of 3.0. The carrier's annual cost for the bond, apart from one-time structuring costs, is the 6% spread on $100 million, about $6 million a year. If a traditional reinsurer quoted a one-year layer at a 7% rate on line, or $7 million, the carrier compares more than price: the bond is locked for three years, has no counterparty credit risk, and may carry basis risk if the trigger is an industry index. Those figures are illustrative, not market quotes.

Why a business buyer should care

You will probably never buy a cat bond, but the market touches your policy in four ways.

• Pricing lag. Property carriers build reinsurance costs into their catastrophe loads. A softer ILS market lowers those costs after renewal, but with a delay, and not uniformly. CRC Group's 2026 market report, as summarized by Artemis on April 10, 2026, described cat wind rates down 20% to 30%. How the pass-through works is covered in how reinsurance pricing flows into business insurance premiums, and what drives the cycle in hard and soft insurance markets: what the cycle means for buyers.
• Capacity in peak zones. Carriers and utilities use cat bonds to fund tail risk in places like Florida and California wildfire territory; American Coastal's Florida named storm bond and the Los Angeles wildfire bond above are examples. See hurricane season and commercial property insurance: what to do before a storm and florida's commercial property insurance market.
• New perils. Sponsors increasingly bundle perils or add cyber. Cyber cat bonds such as Beazley's $300 million PoleStar Re 2026-1 are discussed in systemic cyber risk and cyber catastrophe bonds.
• Reversal risk. A major event that exhausts investors' principal can raise spreads and cut ILS appetite quickly, and the effect shows up at the next The January 1 reinsurance renewals explained: the 2026 results and then in your premium.

Buyers do not face the investors' risk, and cat bond losses do not reduce what your insurer owes you. The bond is a financing tool for the insurer, not a source of exposure for you. For the bigger picture of how risk is moved, start with what is reinsurance, and why it affects your business premium.

Key takeaways

• A cat bond is fully collateralized reinsurance sold to investors: they lose principal only if a defined trigger is hit.
• Triggers range from the sponsor's own losses to industry indices and parametric measures, and the gap between trigger and actual loss is basis risk.
• Artemis reported $65.5 billion outstanding at September 30, 2026, a record $25.6 billion issued in 2025 and $18.9 billion in the first nine months of 2026.
• Softer cat bond pricing pushes traditional property catastrophe reinsurance rates down, and that reaches business premiums with a lag.
• A major catastrophe can reverse the cycle quickly, so capacity for peak-zone property is never guaranteed.