What is a cat bond trigger? The four types explained

Why the trigger matters

A cat bond trigger determines two things: whether the bond pays out, and how quickly. Every other feature of the bond — the coupon, the expected loss, the secondary market price after an event — is influenced by the choice of trigger.

From the sponsor's perspective, the ideal trigger pays exactly when they have a loss, in the exact amount of that loss. That is what an indemnity trigger does. But indemnity triggers are slow, require disclosure, and create moral hazard concerns for investors. Non-indemnity triggers trade away some precision for speed, transparency, and reduced information asymmetry.

From the investor's perspective, the ideal trigger is objective, verifiable, fast to settle, and free of manipulation. Parametric triggers come closest to that ideal, but they introduce basis risk for the sponsor. The choice of trigger is always a negotiation between these competing priorities.

Indemnity triggers

An indemnity trigger pays based on the sponsor's actual reported losses from a covered event. If the sponsor's losses exceed the bond's attachment point, the collateral is released proportionally up to the exhaustion point. This is the closest analogue to traditional reinsurance.

How it works

The bond's terms define a covered peril and territory. When an event occurs, the sponsor reports its losses, typically net of other recoveries. These reported losses are subject to development over time as claims are received, adjusted, and settled. Many indemnity bonds include a loss development period — often 24 to 36 months after the event — during which the reported loss figure can change. An independent auditor usually verifies the final loss figure.

Advantages

Zero basis risk is the primary advantage. The payout matches the sponsor's actual loss experience precisely, which means the bond functions exactly like a reinsurance contract from the sponsor's perspective. This makes indemnity triggers attractive to large insurers with diversified books who need reliable balance-sheet protection.

Disadvantages

Settlement is slow. The sponsor's losses may take 12 to 36 months to develop fully, and investors' capital is locked during this period. There is also an information asymmetry problem: investors depend on the sponsor's reported losses, which the sponsor controls. This creates moral hazard — the sponsor could, in theory, inflate loss estimates or adjust claims-handling practices to maximise the payout. To mitigate this, indemnity bonds typically require the sponsor to retain a portion of the risk and to disclose detailed portfolio information, which some sponsors prefer to avoid.

Typical use

Indemnity triggers are the most common trigger type in the private cat bond market. Large US property insurers and reinsurers favour them because they eliminate basis risk. Florida Citizens Property Insurance Corporation, the state-backed insurer of last resort, has issued multiple series of indemnity-triggered cat bonds (the Everglades Re programme) to transfer Florida hurricane risk.

Industry loss triggers

An industry loss trigger pays based on an estimate of total industry-wide losses from a catastrophe event, as reported by an independent third-party index provider. If the industry loss exceeds the bond's trigger threshold, the payout is calculated according to a formula defined in the bond's terms.

How it works

The bond references a specific loss index. In the US, this is usually the Property Claim Services (PCS) index, which compiles industry loss data from insurers after major catastrophe events. In Europe, the equivalent is PERILS AG. When a qualifying event occurs, the index provider collects loss data from across the market and publishes an aggregate industry loss figure. PCS typically issues initial estimates within a few weeks and updates them over 6 to 18 months.

The bond's payout formula converts the industry loss figure into a loss for the bond, usually based on the sponsor's market share or a fixed percentage. For example, a bond might specify that the sponsor's loss is calculated as 5% of the PCS industry loss, reflecting the sponsor's approximate share of the US property market.

Advantages

Industry loss triggers eliminate the information asymmetry problem. The payout is determined by an independent third party, not the sponsor. This removes moral hazard and means the sponsor does not need to disclose detailed portfolio data. Settlement is faster than indemnity, though still dependent on the index provider's reporting timeline. Investors also benefit from the transparency of a publicly reported number.

Disadvantages

Basis risk. The sponsor's actual losses may differ significantly from what the industry loss formula implies. A sponsor whose portfolio is concentrated in a particular region hit hard by a hurricane might suffer losses well above its market share, but the bond payout is capped by the formula. Conversely, a less-affected sponsor might receive a payout larger than its actual losses.

There is also reporting lag. PCS and PERILS update their estimates over time, and the final figure can differ materially from initial estimates. Investors are exposed to this uncertainty during the development period.

Typical use

Industry loss triggers are common in US wind and earthquake bonds. They are the second most used trigger type in the cat bond market. Sponsors who want a balance between basis risk and transparency often choose industry loss triggers, particularly reinsurers who are comfortable with some mismatch between the index payout and their own experience.

Modelled loss triggers

A modelled loss trigger pays based on the output of a catastrophe model run on a defined portfolio of exposures. The portfolio is fixed at inception and does not change during the bond's term. When an event occurs, the actual event parameters (wind field, ground motion, flood depth) are fed into the model, which calculates what the losses would be for that fixed portfolio.

How it works

At issuance, the bond defines a reference portfolio of exposures — a set of properties, locations, and coverage terms. It also specifies which catastrophe model will be used (historically RMS, AIR, or CoreLogic, now branded as Moody's RMS, Verisk, and CoreLogic respectively). After a qualifying event, the modelling firm collects the event's physical parameters from official sources and runs the model using those parameters against the fixed portfolio. The model output determines the loss to the bond.

The key distinction from an indemnity trigger is that the portfolio is frozen at inception. The sponsor's actual book of business may change over time, but the modelled loss is always calculated on the original fixed exposure set.

Advantages

Modelled loss triggers settle faster than indemnity triggers because they do not require the sponsor's actual claims to develop. Once the event parameters are known and the model is run, the loss figure is determined. This typically takes weeks to a few months. They also reduce information asymmetry compared to indemnity triggers, since the model run is conducted by an independent third party on a pre-defined portfolio.

For sponsors, modelled loss triggers offer less basis risk than industry loss or parametric triggers, because the reference portfolio can be constructed to closely resemble the sponsor's actual exposures at the time of issuance.

Disadvantages

There is still basis risk, because the sponsor's actual portfolio will drift from the fixed reference portfolio over the bond's multi-year term as policies are written, renewed, and cancelled. The model itself introduces uncertainty — different model versions, resolution settings, and vulnerability functions can produce different loss estimates from the same event parameters. Investors need to trust the model, and model risk is a real concern.

There is also a transparency issue: the reference portfolio is disclosed to investors at issuance, but the model's internal workings are proprietary. Investors are, to some degree, relying on a black box.

Typical use

Modelled loss triggers occupy a middle ground and are less common than indemnity or industry loss triggers. They are sometimes used by sponsors who want faster settlement than indemnity but whose risk profile does not map cleanly to an industry loss index. Some European and Asian cat bonds have used modelled loss triggers where no equivalent of PCS exists for the relevant peril.

Parametric triggers

A parametric trigger pays based on a physical measurement of the catastrophe event itself, not on any loss calculation. The bond defines specific physical parameters — sustained wind speed at named weather stations, earthquake magnitude and depth at a defined location, rainfall accumulation over a set period — and if the measured values exceed the trigger thresholds, the bond pays out according to a predefined formula.

How it works

The bond specifies one or more reporting stations or data sources (national meteorological agencies, the USGS for earthquake data, NOAA for hurricane data) and defines the exact conditions that constitute a trigger event. For example, a parametric hurricane bond might specify a payout if sustained wind speed exceeds 120 mph at any of five named weather stations in a defined geographic box. An earthquake bond might trigger if the USGS reports a magnitude 7.0 or greater event with an epicentre within a defined zone.

Some parametric bonds use a binary trigger (full payout or nothing), while others use a parametric index where the payout scales with the severity of the physical measurement. A wind-speed index, for instance, might calculate a weighted average wind speed across multiple stations, with the payout increasing as the index value rises.

Advantages

Speed and objectivity. Because the trigger depends only on a physical measurement reported by an independent agency, there is no loss adjustment, no claims development, and no model run. Payouts can be determined within days of an event, sometimes within hours. This makes parametric triggers particularly valuable where rapid disbursement is critical, such as sovereign disaster financing for developing countries that need emergency funds quickly.

There is also zero moral hazard. The sponsor cannot influence the wind speed or earthquake magnitude, and there is no portfolio data to disclose. This makes parametric bonds highly transparent and attractive to investors.

Disadvantages

Basis risk is the main drawback, and it cuts both ways. The physical measurement may not correlate well with the sponsor's actual losses. A hurricane might register extreme wind speed at a weather station in an unpopulated area while causing most of its damage through storm surge or inland flooding elsewhere. The sponsor could suffer enormous losses from an event that does not meet the parametric threshold, or the bond could pay out for an event that causes little actual loss.

Parametric index triggers reduce this problem somewhat by using weighted measurements across multiple stations, but they cannot eliminate it. Designing a parametric trigger that closely tracks actual losses requires careful calibration, and even well-designed triggers will have basis risk in tail scenarios.

Typical use

Parametric triggers dominate the sovereign and multilateral cat bond space. The World Bank's International Bank for Reconstruction and Development (IBRD) has issued parametric cat bonds on behalf of countries including Mexico, Chile, Colombia, Peru, Jamaica, and the Philippines. The Caribbean Catastrophe Risk Insurance Facility (CCRIF) uses parametric triggers for its hurricane and earthquake coverage across Caribbean nations. These programmes prioritise rapid payout over precise loss matching, because the beneficiary governments using parametric insurance need liquidity within weeks of a disaster, not months or years.

In the private market, parametric triggers are less common but appear in deals where the peril is well-characterised by a single physical measurement, such as earthquake bonds for Japan.

The four trigger types compared

Combinations and variations

Some cat bonds combine trigger types. A bond might use a parametric trigger as an initial qualifying gate — was there a Category 4+ hurricane in the defined region? — and then apply an indemnity or industry loss calculation to determine the payout amount. These hybrid structures attempt to capture the speed and objectivity of parametric triggers while reducing basis risk through a loss-based payout calculation.

Dual-trigger bonds, where two independent conditions must both be met for the bond to pay out, also exist but are rare. For example, a bond might require both a qualifying catastrophe event and a minimum level of industry loss before it triggers.

The market has also seen parametric index triggers become more sophisticated over time. Early parametric bonds used single-station measurements. Modern versions use weighted indices across dozens of reporting stations, with interpolation grids that better approximate the geographic distribution of damage. The World Bank's IBRD earthquake bonds for Mexico, for instance, use a grid-based parametric index that accounts for both ground-shaking intensity and population density.