Reinsurance Panel Design: Size, Line Limits and Security

Reinsurance Panel Design: How Many Reinsurers, What Line Sizes and Which Security Floor?

Last reviewed: November 2026

Reinsurance panel design is the choice of which reinsurers support a programme, how large a share each one takes and the minimum security they must meet. A well-designed panel makes sure a valid claim is paid in full even if one reinsurer cannot pay.

Most panels are built for price and capacity at placement. They are tested only after a large loss, when concentration and weak security become expensive.

This guide is for CFOs, CROs, heads of outwards reinsurance and reinsurance security committees. It sets out how to decide panel size, line limits and security floors, with a worked stress test of two panels.

Key Takeaways

• Panel size should be measured by concentration, using an effective number of reinsurers, not by headcount.
• The most useful line limit caps each reinsurer's full-limit recoverable as a share of the cedent's equity.
• A security floor protects claims-paying ability, but collateral can make lower-rated capacity acceptable.
• AM Best's BCAR criteria give unrated reinsurers a very heavy credit charge unless more information or collateral is provided.
• A small premium saving from weaker security is often wiped out by the capital charge after a loss.
• Long-tail lines need stronger security and tighter concentration than short-tail property.

What Is Reinsurance Panel Design?

Reinsurance panel design sets three things: the number of reinsurers, the size of each line, and the minimum quality each must meet. Each choice trades price against the risk that recoveries are not collected.

A panel is also a relationship structure. A committed lead sets terms, while following markets provide capacity at those terms.

The aim is a panel that pays in full after the worst event the programme is designed for. Everything else is optimisation around that goal.

How Many Reinsurers Should Be on a Panel?

Enough that no single failure would damage the cedent's capital, but few enough that each reinsurer values the relationship. There is no regulatory standard number, so the answer should come from a stress test of the actual programme.

Measure Concentration, Not Headcount

A panel of 20 reinsurers where one takes 40% is more concentrated than a panel of ten equal shares. The Herfindahl index, the sum of squared shares, captures this.

The effective number of reinsurers is one divided by the Herfindahl index. It tells you how many equal-sized reinsurers the panel behaves like.

Balance Diversification With Relationship Value

Very broad panels can dilute each reinsurer's commitment. When a large loss arrives, reinsurers with small lines may be less invested in a smooth settlement.

Hidden links matter too. Reinsurers that share an owner, asset manager or retrocession panel can fail together, as explored in mapping reinsurance counterparty contagion.

What Line Sizes Should Each Reinsurer Take?

Each reinsurer's line should be capped twice: as a share of each layer, and as a full-limit recoverable relative to the cedent's equity. The equity cap is the more important of the two.

Percentage of Layer

A cap such as 15% to 25% of any layer stops one reinsurer dominating a single tranche. It also keeps price discovery healthy across the following market.

Recoverable as a Share of Equity

Add up each reinsurer's share across all layers at full limit, then compare it with equity. A cap expressed this way limits the damage from one failure after the worst event the programme protects against.

Lead and Follow Structure

A lead often takes a larger line in exchange for setting terms. That is reasonable, provided the lead's larger line still respects the equity cap.

Which Security Floor Should a Panel Set?

Many security committees use a floor in the A- range from a recognised rating agency, with exceptions only against collateral, although practice varies. The right floor depends on the tail of the business and how long recoveries take to collect.

How Rating Agencies Charge for Recoverables

AM Best's Understanding Universal BCAR criteria procedure charges for reinsurance recoverables using each reinsurer's AM Best rating and the expected collection period. Reinsurers without a published AM Best rating, or rated ccc+ or lower, receive a 100% impairment rate offset by a 50% recovery rate.

That gives an undiscounted charge of 50%, which the criteria discount for six months at 4%. The charge can be reduced if adequate additional information is provided, including ratings from other agencies, and AM Best considers collateral such as funds held, trusts and letters of credit.

Short-Tail Versus Long-Tail Lines

Property catastrophe recoveries are usually collected within a year or two. Casualty and long-tail recoveries can be outstanding for decades, so the floor should be higher and the review more frequent.

Worked Example: Concentrated vs Diversified Panel

The example below is illustrative and simplified. All figures are in USD millions; the cedent has equity of 400 and a cat programme with 300 of total limit.

The cedent's security policy caps any one reinsurer's full-limit recoverable at 12.5% of equity, which is 50. It also stresses the failure of the largest reinsurer with a 50% recovery.

Panel X looks reasonable with five well-known names. Yet three of its lines breach the equity cap, and one failure would cost twice as much as on Panel Y.

What a Cheaper, Unrated Line Really Costs

Now suppose one of Panel Y's 10% lines, worth 30 at full limit, is offered by a reinsurer with no AM Best rating at a price 10% lower. On a total panel premium of 24, that line costs 2.4, so the saving is 0.24 a year.

The 2% factor for the rated reinsurer is an illustrative assumption, not AM Best's published factor. The unrated factor follows the BCAR treatment described above, before any reduction for other information or collateral.

To save 0.24 a year, the cedent accepts a capital charge of about 14.7 at the moment it can least afford it. If the reinsurer posts collateral, the charge falls and the trade may make sense.

The lesson for cedents: test every panel against the failure of its largest line, and price weaker security in capital, not just premium.

The lesson for reinsurers: expect larger lines to come with tighter scrutiny of your own security, collateral options and concentration with affiliates.

When Should You Choose a Concentrated or Broad Panel?

The right panel shape depends on the line's tail, the size of the programme and how much the cedent relies on a few key relationships. The table maps common situations to the usual choice.

These are starting points. The final design should come from a stress test of the actual panel against the actual programme.

Which Panel Design Mistakes Hurt After a Loss?

Panel weaknesses rarely show at placement. They appear after a large event, when recoverables are at their peak.

How Should Heads of Outwards Build the Panel?

Start from the security policy and stress test, then fill capacity at the best price within those limits. The steps, data and questions below make that practical.

Implementation Steps

1. Set the security floor by line, with collateral rules for exceptions.
2. Set line caps by layer and by full-limit recoverable relative to equity.
3. Aggregate exposure at group level, including affiliates.
4. Place the lead and following lines within those caps.
5. Stress the panel against the failure of the largest line after the design event.
6. Monitor ratings, outlooks and recoverables at least quarterly.

What Data Should the Security Committee Review?

Which Questions Should Be Asked at Renewal?

• Which reinsurer would cause the largest loss if it failed after the design event?
• Has any panel member been downgraded, placed on watch or changed ownership?
• Are collateral arrangements for lower-rated lines current and enforceable?
• How quickly did each reinsurer pay its last large recoveries?

Payment behaviour is easiest to track with a reinsurance receivables ageing dashboard. For reinsurers outside your home jurisdiction, see third-country reinsurance due diligence.

How Does Panel Design Affect Capital and Regulation?

Panel quality directly changes how much capital relief a programme delivers. Weak or concentrated security converts underwriting risk into credit risk rather than removing it.

Article 101(5) of the Solvency II Directive recognises risk-mitigation techniques only where the credit and other risks they create are properly reflected in the SCR. A weaker panel therefore earns less net relief through a higher counterparty default charge.

Rating agencies also assess reinsurance dependence and the quality of reinsurance alongside their capital models. AM Best's BCAR criteria note that a concentration of recoverables with a small number of reinsurers is assessed qualitatively as part of balance sheet strength.

Collateral can bridge the gap where capacity comes from lower-rated or unrated sources. Our guide to reinsurance collateral as a supply chain covers how to track it.

What Does the Market Look Like for 2027?

Reinsurance capacity has been abundant through 2026, and new capacity, including collateralised capital, has competed for lines. That gives cedents more choice on panel composition.

Abundant capacity tempts buyers to accept weaker security for small price gains. The worked example shows why a disciplined floor and equity cap matter most when the market is soft.

Checklist for Heads of Outwards and Security Committees

Use this checklist before you finalise any panel.

• The security floor is set by line and tail length
• Every reinsurer's full-limit recoverable is within the equity cap
• Exposure is aggregated at group level, including affiliates
• The effective number of reinsurers is calculated, not just headcount
• The panel is stressed for failure of the largest line after the design event
• Collateral for exceptions is in place, enforceable and tracked
• Ratings, outlooks and recoverables are monitored at least quarterly
• Premiums and claims are allocated and reconciled by reinsurer share

For the last point, bordereaux reconciliation splits premiums and claims across participating reinsurers by share and checks them against the underlying records.

Key Terms

Reinsurance panel: The group of reinsurers that together support a treaty or layer.

Line size: The percentage share of a layer or treaty taken by one reinsurer.

Security floor: The minimum financial strength rating a reinsurer must hold to join the panel without collateral.

Herfindahl index (HHI): The sum of the squared shares of all panel members. Higher values mean more concentration.

Effective number of reinsurers: One divided by the Herfindahl index. It shows how many equal-sized reinsurers the panel behaves like.

Equity cap: A limit on any one reinsurer's full-limit recoverable, expressed as a percentage of the cedent's equity.

Lead reinsurer: The reinsurer that sets price and terms, which following markets then accept.

Collateral: Assets such as trust funds, letters of credit or funds withheld that secure a reinsurer's obligations.

Sources

• AM Best: Understanding Universal BCAR (criteria procedure)
• Directive 2009/138/EC (Solvency II), EUR-Lex
• EIOPA: Solvency II resources
• International Association of Insurance Supervisors (IAIS)