Cat bonds
Investors buy notes. Their capital backs protection for specified risks and can be reduced when the payout conditions are met.
This primer’s main focusA PRIMER / ABOUT 12 MINUTES
Cat bonds,
made clear.
How capital markets help carry the financial risk of a catastrophe.
A hurricane can create more claims than an insurer wants to hold on its own balance sheet. A catastrophe bond brings in investor capital to absorb a defined slice of that risk.
Follow the moneyI spent years at Swiss Re working with the people and payments behind these deals, then led product for ACP iLink, a platform connecting deal participants. This is the introduction I would give someone curious about how the market works.
THE BIGGER PICTURE
Where cat bonds fit.
Insurance-linked securities (ILS) connect investor capital with insurance risk. Investors earn a return for carrying that risk. In market conversation, ILS also covers private ways of investing in insurance risk, beyond bonds.
Investor capital → insurance riskThe wider ILS market
Collateralized reinsurance
Investors fund a private reinsurance contract, with money set aside to pay covered claims. It does not need to be issued as a tradable bond.
Sidecars
A separate vehicle lets investors share an agreed slice of an insurer’s or reinsurer’s premiums and losses.
Other insurance risks
ILS can also transfer risks tied to mortality, longevity or other insurance exposures. These describe the risk being funded, not one single legal structure.
NAIC: ILS and related structures · Swiss Re: the broader investment toolkit
01 / THE ECONOMICS
How big is this market?
What has it paid?
Two different numbers tell the story. Outstanding is investor money still backing live bonds. Return is what a basket of bonds earned after coupons and price moves.
CAPITAL STILL AT RISK / USD
Live cat bonds and related ILS notes tracked by Artemis, including private deals and some non-catastrophe risks. This is not the whole ILS market. New deals add capital; maturities and principal losses remove it. Figures are dated snapshots. Source: Artemis reports.
THREE COMPLETED YEARS / TOTAL RETURNWhat the market
What the market
basket earned.
202319.69%
202417.3%
202511.4%
Swiss Re Global Cat Bond Total Return Index, calendar years 2023–2025. Coupons and price changes included. These unusually strong years are history, not a forecast. Index returns are not an individual fund’s returns and do not include its fees.
Follow the growth.
Move the starting amount. See how those three annual returns compound.
Start of 2023$100.00
→End 2023$119.69
→End 2024$140.40
→End 2025$156.40
A calculation using published index returns, with reinvestment. Not a fund you can buy directly; no fees, taxes or trading costs deducted. An individual bond can lose principal even when the index rises.
A MADE-UP $100 BOND
Where does the coupon come from?
Imagine the collateral earns $4 in a year, and the sponsor’s premium funds $7 of risk spread. That makes an $11 coupon before fees and other deal costs. The extra $7 is payment for putting the $100 at risk.
$4 collateral
income+$7 risk
spread=$11 illustrative
coupon
income+$7 risk
spread=$11 illustrative
coupon
A coupon is the interest payment under the bond’s terms. A loss or extension can change future payments. The coupon alone does not tell you the final return: the bond’s price can move, and a catastrophe can cut or wipe out the $100 principal. The numbers above are an illustration, not a market quote.
02 / THE MECHANICS
A bond on one side.
Protection on the other.
The common structure uses a special-purpose vehicle (SPV): a separate issuer that connects the protection contract with the bond investors.
A TYPICAL DEAL / INVESTOR MONEY SET ASIDE
01
Sponsor
Insurer, reinsurer, corporation or public entity
Protection contract→
02
SPV / issuer
Issues the notes and provides the contracted protection
Investor principal←
03
Investors
Typically ILS funds and institutional investors
Collateral account
Investor proceeds are held separately in permitted collateral, commonly short-term, high-quality assets.
01 / CAPITAL IS COMMITTED
Investors buy the notes. Their principal funds the collateral account, backing the SPV’s obligations to the sponsor.
The coupon. Typically collateral or floating-rate income plus a risk spread funded by the sponsor’s premium. The spread compensates investors for catastrophe exposure.
The endpoint. With no principal loss, capital is returned at maturity. A qualifying loss reduces principal; final settlement or extensions can delay the return of remaining capital.
Does every cat bond use this structure?
No. The World Bank can issue capital-at-risk notes directly and enter an insurance or derivative agreement with its client, without a separate SPV. Fronting insurers or reinsurers may also sit between a sponsor and an SPV. The diagram above deliberately shows the common, simplified route.
03 / DEAL DESIGN
“Deal type” has
more than one dimension.
Read a deal through three questions: whose risk is transferred, what losses count, and what determines the payout.
Insurance, reinsurance
or retrocession
Insurance: protection for a corporation, public entity or other exposed buyer, sometimes through an intermediary.
Reinsurance: an insurer transfers part of the risk it has written.
Retrocession: a reinsurer transfers part of the risk it has assumed.
Occurrence
or aggregate
Per occurrence: responds to a single qualifying event above the agreed threshold.
Aggregate: qualifying losses accumulate across events within a defined period, subject to the deal’s deductibles and conditions.
Some deals cover the second or later event. A deal can be split into separate pieces, called tranches, each covering its own slice of risk.
Perils, places
and time
A deal may cover one peril or several, across one or more regions. Examples include US hurricanes, Japanese earthquakes and European windstorms.
Coverage often lasts around three years. The contract also says what is excluded and whether the covered risks or terms can change during that time.
Four ways to determine a payout
A damaging event does not automatically trigger a bond. The agreed metric and threshold have to be met.
Indemnity
Uses the sponsor’s actual covered losses.
Closer alignment with the sponsor’s losses; claims development can take time.
Industry loss
Uses an independent estimate or index of insured losses across the industry.
An external benchmark; the sponsor’s losses may differ from the index.
Parametric
Uses physical event measurements, such as earthquake magnitude and location or storm intensity.
Can support faster determination; physical severity may not match actual losses.
Modeled loss
Runs the event through a specified model and exposure portfolio to calculate a loss.
A prescribed calculation; results depend on the model and exposure assumptions.
Basis risk is the gap between a sponsor’s actual loss and the protection payout. It is particularly relevant when the trigger uses an index, event parameters or modeled losses.
How is the risk legally transferred?
The protection side may be documented as insurance, reinsurance, retrocession or a catastrophe derivative, depending on the parties and structure. The notes fund that protection. Trigger type describes how the payout is determined; it is a separate choice from the legal form.
Outside cat bonds, the wider toolkit includes traditional reinsurance, collateralized reinsurance, industry-loss warranties and sidecars. These are related ways to transfer or share insurance risk, with different contracts, funding and liquidity.
04 / RISK IN PRACTICE
Only a defined
slice of the loss.
Imagine a $100 million bond covering a layer of eligible losses from $500 million to $600 million. Move the loss amount to see who absorbs this layer.
ILLUSTRATIVE INDEMNITY DEAL / USD
$400m$700m
Below attachment
$0–500m
$0–500m
Bond’s layer
$500–600m
$500–600m
Above exhaustion
$600m+
$600m+
Below and above this layer, the sponsor retains risk or buys other protection. Attachment is where this layer starts paying; exhaustion is where its $100m limit is fully used.
Simplified illustration: 100% participation in this layer, no additional deductibles, fees, reinstatements or timing effects. Eligible loss means loss recognized under the contract, not total economic damage. Actual payout rules vary.
ACTUAL PRINCIPAL LOSSES
Good market returns.
Real losses on some bonds.
A market index holds many bonds. One can pay out while the wider basket still earns a positive return. Here are selected loss events from 2021–2025, the last five completed calendar years.
Principal lostPrincipal not lost in this example
2021 EVENT
Philippines / IBRD CAR 124 Class B
Typhoon Rai (Odette), December 2021
35% principal loss$52.5m of $150m
Reported payout; remaining principal later matured without further loss. Source ↗
2022 EVENT
Integrity Re II (2020-1), Class A
Hurricane Ian, September 2022
2023 EVENT
Mexico / IBRD / FONDEN 2020 Class D
Hurricane Otis, October 2023; payout in 2024
2025 EVENT
Jamaica / IBRD CAR 2024
Hurricane Melissa, October 2025
Each bar represents the original principal of one named tranche, not an investor’s whole portfolio. These are selected examples, not every loss or an annual market loss rate. Event years can differ from payout years. A low trading price or extended maturity is not, by itself, a final principal loss. Sources checked October 7, 2026.
Explore Artemis’s loss and at-risk directory ↗05 / THE PEOPLE
A whole team
behind each deal.
Sponsor / protection buyer
Defines the risk it wants to transfer and pays the premium. It often retains substantial exposure alongside the bond.
Arranger & bookrunner
Helps design the transaction, coordinate diligence, market the notes, establish pricing and place them with investors.
Issuer, banks & service providers
The SPV signs the contracts. Trustee banks safeguard the collateral and help handle payments. Administrators keep the vehicle running; lawyers prepare the documents. Each role has defined duties.
Catastrophe modeler
Uses disaster simulations and data about insured properties to estimate how often a bond could lose money and how much it might lose. The model is a map of possibilities, not a prediction of the next disaster.
Reporting & calculation agents
After an event, a reporting source supplies the measurements or loss figures named in the deal. A calculation agent applies the bond’s rules to decide whether and how much it pays. The exact jobs depend on the trigger.
Rating agency, if used
Some issuers seek a rating to help investors compare risk; others are unrated. A rating is an opinion about the bond’s risk, not a promise that its principal is safe.
Investors & ILS managers
Assess the disaster risk, location, model estimates, price and contract terms. Managers build portfolios and may trade the notes in the secondary market.
Policyholders & communities
Usually benefit downstream, rather than owning the bond. Insurers still handle policy claims; public-sector sponsors deploy disaster-response funds.
WHAT AN INVESTOR MIGHT OWN
How a portfolio spreads risk.
An ILS manager might buy many bonds, with different sponsors, places, disasters, risk layers and payout rules. Here is a made-up ten-bond basket. It shows the idea, not a recommended mix or actual market weights.
Four US hurricane bonds still share a lot of storm risk. Ten names do not mean ten independent risks.
US hurricane
4
US earthquake
2
Japan quake / typhoon
2
European wind
1
Mexico / Caribbean
1
What I learned from the operating side
At Swiss Re, I created flow-of-funds templates and coordinated investors, sponsors, banks and other providers through settlement. Leading product for iLink brought those workflows into one platform.
A bond keeps creating work after it is issued: payments, reporting dates, changes to the covered risks and loss notices. The parties need a shared view of what is due, who owns it and what changed. That is the practical detail behind the structure diagram.
06 / WHY IT MATTERS
Different participants.
A connected purpose.
A different
source of return.
Earn a spread for bearing catastrophe risk and diversify away from risks driven primarily by corporate credit or economic activity.
The attraction is a compensated insurance exposure. Low historical correlation is useful, but it is not a guarantee.
More capacity.
More options.
Access capital beyond traditional reinsurance, often with multiyear protection. Prefunded collateral reduces reliance on an investor’s ability to pay after a disaster.
Cat bonds complement a risk-financing program. Execution costs, market pricing and contract fit still matter.
Support for the
promise to pay.
Additional risk-bearing capacity can help insurers withstand severe events and keep coverage available. Public-sector deals can fund emergency response and recovery.
Benefits are indirect: a cat bond does not guarantee cheaper premiums, broader policy coverage or faster individual claims payments.
The tradeoff is real.
Investors can lose their entire principal. Catastrophe models are estimates, exposures and climate conditions change, and portfolios can concentrate in the same perils. Secondary-market liquidity may weaken, prices can fall, and capital can remain tied up while losses are settled.
07 / BEYOND THE BOND
What is a sidecar?
Imagine a reinsurer writing a book of business. It can invite outside investors to share a set percentage of that book’s premiums and losses through a separate vehicle. That vehicle is a sidecar.
REINSURERFinds and manages the business
→SIDECARTakes an agreed share
←INVESTORSPut up capital and share results
Why use one? A reinsurer can write more business without funding every dollar of risk itself. It may also earn fees for underwriting or managing the book. Investors get access to the reinsurer’s underwriting, with the losses that come with it.
How is it different? A cat bond usually covers a defined layer of loss for named risks. A sidecar commonly shares a slice of a portfolio. This is often a quota share: an agreed percentage of premiums and losses. Its terms, liquidity and return can look quite different. Sidecar definition
WHERE IS THE BOND ISSUED?
Why Bermuda shows up so often.
Bermuda already had a large reinsurance industry. Its regulator introduced a special-purpose insurer framework in 2009. The island also has lawyers, managers, trustees and market specialists who know these deals. That makes it a familiar place to set up the issuing vehicle.
Other deals use places such as Ireland or Singapore, and the World Bank can issue notes directly. The legal home of the issuer can differ from where the disaster risk sits or where investors live.
Bermuda regulator · Ireland’s SPV framework · Singapore’s reinsurance vehicles
A REAL-WORLD EXAMPLE
Jamaica / 2024
The World Bank issued a $150 million cat bond providing Jamaica with named-storm protection for four hurricane seasons. Its parametric trigger uses location and severity criteria, supporting access to disaster-response funding when those terms are met.
Read the transaction announcementHurricane Melissa later triggered a full $150 million payout in 2025. The named loss example above shows the investor side of that protection.
08 / RESILIENCE IN PRACTICE
Designing protection
around the need.
The useful innovation is getting money to the right place when it is needed. That starts with deciding what needs protection, what should trigger payment, and how the money will support recovery.
These examples use different tools. The reef and farmer programmes below are insurance, not cat bonds. They show how the wider risk-transfer toolkit can support resilience.
Storm threshold↓Insurance payout↓Funds for reef repair
Protect what
protects the coast.
A reef helps soften waves before they reach the shore. In Quintana Roo, Mexico, hurricane insurance was designed to fund repairs to part of the Mesoamerican Reef.
Hurricane Delta triggered a payout of nearly $850,000 in 2020, helping fund reef repair and restoration. The protection had a specific job: give the response team money to act after a storm.
The Nature Conservancy: reef insurance ↗Weather threshold↓Insurance payout↓Funds for recovery
Help a bad season
stay recoverable.
Weather-index insurance can pay when agreed weather thresholds are reached, rather than waiting to assess every farm’s losses.
The World Food Programme’s R4 initiative uses index-based agricultural insurance alongside better farming practices, savings and access to credit. Its products include weather, area-yield and hybrid indices. A payout can help a family recover without selling the tools or livestock it needs for the next season.
This example is an insurance policy, not a cat bond or a weather derivative. The index may differ from a farmer’s actual loss. That gap is basis risk.
WFP: rural resilience ↗Outbreak occurs↓Check contract conditions↓Payment only if met
The trigger has
to fit the need.
After the West African Ebola crisis, the World Bank launched pandemic bonds in 2017 to help fund responses to severe outbreaks.
The later 2018–20 Ebola outbreak in the Democratic Republic of Congo did not meet the insurance window’s cross-border conditions, so that window did not pay. A separate cash window did provide support.
The lesson matters: arranging capital is only part of the job. The payout conditions must fit the emergency the funding is meant to address.
World Bank: how the facility worked ↗MY VIEW FROM THE OPERATING SIDE
What I saw break down.
The contract can be precise while the work around it is fragmented. At Swiss Re, investors, sponsors, brokers, banks and administrators often held different parts of the same picture. Documents, dates, pricing and next actions were spread across files, email and separate systems.
Information is scattered
→People rebuild the deal picture by hand.
Changes are hard to trace
→Which version is current? What changed?
Ownership is unclear
Who needs to act, and by when?
iLink: make the shared work visible.
I led product for ACP iLink to bring documents, pricing, timelines and accountability into one working view. A shared calendar and clear next actions helped participants coordinate the life of a deal.
The product problem was making the same information reachable and the next owner obvious, so people could spend less time reconstructing the picture.
See the iLink decisions →Luce: keep the answer connected to evidence.
Luce is a personal experiment exploring the next question: can fragmented deal documents become easier to query without hiding where an answer came from?
The prototype puts a plain-language question, market context and the original source next to each other. It uses simulated and sanitized data. I’m exploring how to make the evidence inspectable, rather than asking someone to trust a confident-looking answer.
Explore the Luce experiment →For me, transparency means being able to see the source, understand what changed and know who owns the next action. A shared view is useful when people can check it.