Risk aggregation is the approach used to calculate the total of each and all of the risk elements. A diversification credit or benefit results when the aggregation of risks produces results that are less than the total of the individual risk elements.
11.1. Withinrisk diversification
Diversification credits are applied to specific components of the mortality and morbidity requirements calculated in Chapter 6. The credit in section 11.1.1 is calculated net of registered reinsurance. Within the calculation of the Base Solvency Buffer used to determine the LICAT ratios, the statistical fluctuation factors in section 11.1.2 are calculated net of registered reinsurance. For the solvency buffers
SB_{1},
SB_{2} and
SB_{3} defined in section 6.8, statistical fluctuation factors are calculated net of registered reinsurance and additional elements specific to the calculation. Since the requirements for participating business are calculated on a standalone basis (q.v. section 9.1.2), there are no withinrisk diversification benefits between similar risks in participating blocks and nonparticipating blocks.
11.1.1 Mortality level and trend risk  diversification credit between life supported and death supported business
A diversification credit is calculated between individually underwritten life supported and individually underwritten death supported business. The diversification credit is determined by first calculating mortality level and trend risk components for individually underwritten life supported business and death supported business in aggregate. The aggregate component for level and trend mortality risk assumes a correlation factor of 75% between life and death supported business and is calculated as:
where:

RC_{aggregate} is the aggregate component for mortality level and trend risk (after diversification) for all life and death supported business;

RC_{L} is the sum of the individual risk charges for mortality level risk and mortality trend risk for life supported business as determined in sections 6.2.2 and 6.2.3, respectively;

RC_{D} is the sum of the individual risk charges for mortality level risk and mortality trend risk for death supported business as determined in sections 6.2.2 and 6.2.3, respectively.
The diversification credit is the difference between the sum of the individual mortality level and trend risk components for life supported and death supported business (qq.v. sections 6.2.2 and 6.2.3) and the aggregate component for mortality level and trend risk calculated using the formula above:
Diversification credit =
RC_{L} +
RC_{D} 
RC_{aggregate}
11.1.2 Morbidity risk credits
The capital requirements for morbidity risk determined in section 6.4 for certain products are reduced by multiplying the requirement by a statistical fluctuation factor (SFF). For each SFF, exposures are aggregated by product within each geographic region before the SFF is applied. For example, all disability exposures within a geographic region are aggregated (individual active DI, individual active WP, individual disabled DI, group disabled LTD, individual and group disabled WP and group active and disabled STD) before the SFF is applied.
11.1.2.1 Credit for level risk
Morbidity SFFs for level risk are calculated as follows:
Disability
where
RC is the capital requirement for level risk.
CI
where
FA is the total face amount.
LTC
where
RC is the capital requirement for level risk.
11.1.2.2 Credit for volatility risk
Morbidity SFFs for volatility risk are calculated as follows:
Disability
where
RC is the capital requirement for volatility risk.
CI
where
FA is the total face amount.
LTC
where
RC is the capital requirement for volatility risk.
Travel and credit
where
RC is the capital requirement for volatility risk.
Medical/Dental (including other group A&S)
where
RC is the capital requirement for volatility risk.
11.1.3 Mortality and morbidity risks – portfolio volume credit
A credit is given for diversification across geographic regions in the level risk component of the mortality and morbidity requirements. For each of the mortality, morbidity incidence, and morbidity termination requirements for a block of business within a region, the component for level risk may be reduced by:
0.5 x (L_{0} 
L_{1})
where
L_{0} is the level risk component for the block calculated using the volatility and statistical fluctuation factors for its region, and
L_{1} is the level risk component for the block calculated using volatility and statistical fluctuation factors based on business volumes aggregated across all geographic regions. Both
L_{0} and
L_{1} are calculated net of all reinsurance.
11.2 Betweenrisk diversification
After the individual risk components have been calculated, they are aggregated in three stages. First, a postdiversification requirement for insurance risk (I) is calculated. Then, an unadjusted diversified requirement for all risks (D) is calculated by aggregating the net requirement for insurance risk with the requirements for credit risk and market risk. This unadjusted diversified requirement is compared against the undiversified requirement (U) calculated as the sum of individual risk components. The adjusted diversified requirement (K) is calculated based on
D and
U.
If an insurer wishes to take credit for participating or adjustable products (q.v. Chapter 9), or for unregistered reinsurance or reinsurance claims fluctuation reserves (q.v. section 6.8), it will be necessary to calculate the quantities
I,
D,
U and
K for one or more subsets of the insurer's book of business.
11.2.1 Insurance Risk Requirement (I)
The requirement for insurance risk
I is calculated by aggregating the components of insurance risk using a correlation matrix. The formula for
I is:
where:

IR_{i} is the required capital for insurance risk
i, before credit for participating and adjustable products,

LT_{i} is the sum of the level and trend components for insurance risk
i (LT_{7}, the level and trend component for expense risk, is zero)

PC is the requirement for any P&C risks arising from consolidated subsidiaries that write both life and P&C business (q.v. section 6.7)

ρ_{ij} is the correlation factor between insurance risks
i and
j, as specified by the following correlation matrix:
 Mortality  Longevity  Morbidity incidence and claims  Morbidity termination  Lapse sensitive  Lapse supported  Expense 

Mortality  1       
Longevity  0.25  1      
Morbidity incidence and claims  0.5  0.25  1     
Morbidity termination  0.25  0.5  0.25  1    
Lapse sensitive  0.25  0.25  0.5  0.5  1   
Lapse supported  0  0.25  0  0.25  0.5  1  
Expense  0.5  0.25  0.5  0. 5  0.5  0.25  1 
However,
I may not be lower than the highest value of
IR_{i}  0.5 x
LT_{i} + PC for any insurance risk
i included in the correlation matrix.
11.2.2 Diversified Risk Requirement (D)
The unadjusted diversified requirement
D for all risks is calculated by aggregating the requirements for credit and market risks with the insurance risk requirement. The correlation assumed between the two classes of risks is 50%. Consequently:
where:

A is the sum of the requirements for credit risk (for both on and offbalance sheet items) and market risk, and

I is the insurance risk requirement from the previous section.
11.2.3 Undiversified Risk Requirement (U)
The undiversified risk requirement
U is calculated as:
where
IR_{i} A and
PC are as defined in sections 11.2.1 and 11.2.2.
11.2.4 Adjusted Diversified Requirement (K)
After the diversified and undiversified risk requirements
D and
U have been computed, the adjusted diversified requirement
K for insurance, credit and market risk is calculated as:
where:
Example: Calculation of the Adjusted Diversified Requirement
Suppose that the life insurance risk requirements for a nonparticipating block of business in a geographic regions, with corresponding level and trend components, are as follows:
Life insurance risk 
Gross component (IR_{i}) 
Level and trend components (LT_{i}) 
Mortality  1,000,000  700,000 
Longevity  3,000  3,000 
Morbidity incidence  50,000  10,000 
Morbidity termination  2,500  1,000 
Lapse sensitive  300,000  150,000 
Lapse supported  100,000  40,000 
Expense  10,000  0 
Totals  1,465,500  904,000 
Suppose as well that the block's other risk requirements are as follows:
Risk 
Component 
Credit risk  200,000 
Market risk  75,000 
Property and casualty risk  25,000 
In order to calculate the total requirement
K for the block, it is first necessary to calculate the quantities
IR_{i} − 0.5 ×
LT_{i} for each of the life insurance risks:
Insurance risk 
IR_{i} − 0.5 ×
LT_{i} 
Mortality  650,000 
Longevity  1,500 
Morbidity incidence  45,000 
Morbidity termination  2,000 
Lapse sensitive  225,000 
Lapse supported  80,000 
Expense  10,000 
The insurance risk requirement
I is calculated by aggregating the components of the above using the correlation matrix specified in section 11.2.1, and adding the requirement for property and casualty risks:
Since the highest value of
IR_{i} − 0.5 ×
LT_{i } +
PC is 675,000, the value of
I is not increased to account for this minimum.
The requirements for credit and market risk are summed to obtain
A:
after which it is possible to compute the diversified risk requirement
D:
The undiversified risk requirement
U is:
The last quantity needed to calculate
K is
LT, given by:
With
D,
U and
LT known, the final adjusted diversified requirement
K is calculated as:
11.3 Base Solvency Buffer
The Base Solvency Buffer is equal to:
where:
 γ is the scalar defined in section 1.1.5
 ∑K_{nonpar} is the sum of the requirements
K calculated for the nonparticipating block in each geographic region
 The second sum is taken over all qualifying participating blocks, and the third sum is taken over all qualifying adjustable products

K_{par i} is the standalone adjusted diversified requirement
K for qualifying participating block
i

CP_{i} is the par credit for participating block i calculated under section 9.1.2

CA_{j} is the adjustable credit for adjustable product
j calculated under section 9.2.2

CG is the total of all credits for policyholder deposits and group business under sections 6.8.2 and 6.8.3

SFG is the capital requirement for segregated fund guarantee risk

OR is the capital requirement for operational risk.