What is the asset swap spread and how is it used to assess relative value in fixed income?

The asset swap spread (ASW spread) is the spread over a reference rate (like SOFR or EURIBOR) that an investor earns by entering into an asset swap — buying a bond and simultaneously entering an interest rate swap to convert fixed coupons to floating.

Asset Swap Mechanics:

1. Buy a fixed-rate bond at its market price (say 95% of par)
2. Enter an interest rate swap where you:

• Pay the bond's fixed coupon to the swap counterparty
• Receive SOFR + ASW spread from the counterparty

1. At maturity, receive par from the bond

The ASW Spread Compensates For:

• Credit risk of the bond issuer
• The bond's price deviation from par (par/off-par adjustment)
• Any embedded options

Calculation Example:

Merrifield Corp 5-year bond:

• Coupon: 5.0% (annual)
• Market price: 96.5 (below par)
• 5-year swap rate: 4.2%
• Bond yield: 5.78%

Simplified ASW spread:

ASW spread (approx) = Bond yield - Swap rate = 5.78% - 4.2% = 158 bps

But the exact calculation adjusts for the purchase at a discount:

The investor pays 96.5 for the bond but receives par (100) at maturity. This 3.5-point gain is amortized over 5 years, adding approximately 70 bps/year. However, the swap is structured at par, creating a present-value adjustment.

ASW Spread vs. Z-Spread:

When to Use ASW Spread:

1. Bank portfolios: Banks fund at SOFR, so ASW spread directly measures the carry over funding costs
2. Relative value across issuers: Compare ASW spreads of similarly rated bonds to identify cheap/rich securities
3. Basis trading: If ASW spread diverges from CDS spread, a basis trade opportunity exists

Basis Trade Opportunity:

If ASW spread = 160 bps but CDS spread = 130 bps:

• Buy the bond + asset swap (earn 160 bps)
• Buy CDS protection (pay 130 bps)
• Net carry = 30 bps with hedged credit risk

CFA Exam Tip: Know when ASW spread vs. Z-spread is appropriate and understand the basis trade concept.

Practice fixed income relative value in our CFA question bank.