Excess-of-Loss Reinsurance
Definition
Excess-of-loss reinsurance is non-proportional reinsurance that pays the insurer's losses above a retention (the attachment point) up to a stated limit. Cover can apply per risk, per occurrence (one catastrophe event) or in aggregate (all qualifying events in a period). Programs are built as stacked layers, each with its own retention, limit, price and reinstatement terms; most cat bonds and collateralized reinsurance contracts sit in one of these layers.
Why it matters
Where a layer attaches decides how often it pays and how much it costs. Low layers are hit often and pay more premium; high layers are rarely hit, cheaper, and lose everything when they are. Investors in cat bonds and collateralized reinsurance are almost always taking a specific excess-of-loss layer, so retention, limit, reinstatement and aggregation terms describe the risk better than the instrument's name.
Common misconceptions
- •A high retention does not make a layer safe; it makes losses rarer but often total when they occur.
- •One event does not exhaust only one layer. A large catastrophe can run through several.
- •Aggregate cover is not the same as per-occurrence cover with a higher limit; many small events can trigger it.
- •The label is only a starting point. Investor outcomes usually depend on the governing documents, cash-flow priority, valuation policy, disclosure quality, and manager discretion surrounding the term, not just the shorthand definition used in marketing materials.
Technical details
Worked example: Allstate's 2025 nationwide program (10-K Note 11)
Per occurrence: up to $9.51 billion of loss less a $1.00 billion retention.
Traditional market: $6.08 billion of placed limits, including $3.24 billion exhausting at $4.25 billion with one annual reinstatement.
ILS market: $2.70 billion of placed limits with no reinstatement.
Aggregate: up to $500 million for events above a $50 million deductible per event.
Modeled 1-in-100 probable maximum loss net of reinsurance: about $3.1 billion. Total program cost in 2025: $1.23 billion.
Layer arithmetic
A layer of $500 million excess of $2.0 billion pays nothing on a $1.9 billion loss, $300 million on a $2.3 billion loss and its full $500 million on any loss of $2.5 billion or more.
Investors in that layer lose 0%, 60% or 100% of principal in those cases if it is a cat bond.
How investors apply the term
Investors usually apply this term by tying the definition back to the controlling documents and then asking which cash flows, rights, restrictions, or valuation assumptions it changes. A useful review looks at the term alongside fees, leverage, liquidity, reporting frequency, and manager discretion rather than treating it as a standalone concept.
The practical diligence test is simple: identify who benefits if the assumption is wrong, who has control when conditions change, and what evidence the investor receives after closing. Terms that cannot be reconciled to documents, cash movements, and monitoring data should be treated as marketing shorthand until proven otherwise.
Frequently asked questions
- What is a retention?
- The amount of loss the insurer keeps before the cover starts. Allstate's 2025 nationwide program covers a single event 'up to $9.51 billion of loss less a $1.00 billion retention.'
- What is a reinstatement?
- A restoration of a layer's limit after it has paid a loss, often for an extra premium, so it can respond to a second event. Allstate's traditional layers include contracts with one annual reinstatement; its ILS placements carry no reinstatement.
- Per occurrence or aggregate?
- Per occurrence cover responds to one event above its retention. Aggregate cover adds up qualifying losses over a period: Allstate's program includes aggregate coverage up to $500 million for events above a $50 million per-event deductible.