Explanation

This question reinforces the relationship between interest rate volatility and OAS for callable bonds.

For callable bonds:

• Higher volatility increases the value of the embedded call option
• The call option benefits the issuer, not the bondholder
• As the call option becomes more valuable, the bond becomes less valuable to investors
• To maintain the same market price with lower theoretical value, the OAS must decrease

Mathematical relationship:

• OAS = Required spread after adjusting for embedded options
• Higher volatility → Higher option value → Lower bond value → Lower OAS needed to explain market price

Intuitive explanation: When volatility increases, the issuer's call option becomes more valuable because there's a higher probability that interest rates will fall enough to make calling the bond profitable. This increased optionality reduces the bond's value to investors, so the spread compensation (OAS) they require decreases.

This is a fundamental principle in fixed income analysis: embedded options affect bond pricing, and OAS properly accounts for these option values.