Risk Factor (Fixed Income) Attribution Models

Why is there no standard fixed income attribution model? 

When it comes to bond returns, the relationship may not be linear and will be affected by multiple factors. Some of the challenges in factor selection include the fact that: 

• Bonds pay regular coupons, even when market performance is down
• Bonds are related to one or multiple curves
• Bonds can default
• Bonds contain some optionality 

Fixed income portfolios also contain more types of and more complex securities than equity portfolios, containing bonds, bond futures, IRS, CDS and currency forwards. 

For these reasons, there is no standard attribution model for fixed income covering the whole variety of instruments and taking into account all the specific features of the instruments involved. 

What are the main fixed income attribution models? 

1.  Sector based attribution
   
   Decomposes active returns into bond market sector allocations and security selections within each sector, similar to the Brinson model for equities. This is the most limited fixed income attribution model.
   
   
2. Factor based attribution
   
   Covers a wider set of investment decisions than sector based attribution. These factors are usually linked to specific stylised movements of the yield curve driving the performance of the fixed income instruments.
   
   
3. Strategy based attribution
   
   In this approach, the portfolio manager will group together the instruments that are used for the same objectives or that reflect a specific market view held by the portfolio manager.
   
   In this type of attribution, every investment decision is recorded in advance. The performance outcome is measured individually. The attribution report will look like a ledger of implemented decisions with their outcomes.