Negative
convexity risk in financial markets arises from several key factors. These factors include the presence of embedded options,
interest rate changes, prepayment risk, and the impact of market
liquidity.
One of the primary contributors to negative convexity risk is the presence of embedded options in financial instruments such as bonds or mortgage-backed securities (MBS). These options give the issuer or the holder the right to buy or sell the
underlying asset at a predetermined price within a specified period. Common embedded options include call options, put options, and prepayment options.
When interest rates decline, bondholders are more likely to exercise their call options, resulting in the issuer redeeming the bonds before
maturity. This leads to a decrease in the duration of the
bond, causing its price to rise less than proportionally to the decrease in interest rates. As a result, the bond exhibits negative convexity. Conversely, when interest rates rise, the likelihood of
call option exercise decreases, and the bond's duration increases, causing its price to fall more than proportionally to the increase in interest rates.
Another factor contributing to negative convexity risk is
interest rate changes. When interest rates decrease, bond prices tend to rise, but at a decreasing rate due to negative convexity. Conversely, when interest rates increase, bond prices tend to fall, but at an increasing rate due to negative convexity. This asymmetrical relationship between interest rate changes and bond prices can lead to significant losses for investors holding bonds with negative convexity.
Prepayment risk is another crucial factor that contributes to negative convexity risk, particularly in mortgage-backed securities (MBS). MBS are pools of mortgages that are securitized and sold to investors. Homeowners have the option to prepay their mortgages when interest rates decline, either by refinancing or selling their homes. As a result, MBS investors face the risk of early
principal repayment, which reduces the duration of the security and increases its negative convexity.
Market liquidity also plays a role in negative convexity risk. In illiquid markets, the bid-ask spreads widen, making it more difficult to buy or sell securities at favorable prices. This can exacerbate negative convexity risk as investors may struggle to exit positions or hedge against adverse market movements. Additionally, illiquidity can lead to price dislocations and increased
volatility, further amplifying negative convexity risk.
In summary, the key factors contributing to negative convexity risk in financial markets include the presence of embedded options, interest rate changes, prepayment risk, and market liquidity. Understanding and managing these factors are crucial for investors and financial institutions to effectively mitigate the potential losses associated with negative convexity risk.