请求讲解A选项错误的原因

问题如下：

A portfolio manager is creating a bond fund with an ESG tilt. In constructing the portfolio, the manager will:

选项：

A.be limited to short-term maturities to avoid climate risk.

B.be able to select green bonds based on a universally accepted ranking system.

C.have a smaller investable universe to select from for sovereign bonds compared to corporate bonds.

解释：

C is correct. An ESG-tilted portfolio could hold both corporate and sovereign debt, but the investable universe for sovereign debt is much smaller than the number of corporates that issue corporate debt. While sovereign debt outstanding in money terms is exceptionally large, the number of sovereign issuers is far lower than the number of corporate issuers. There is not currently a universally accepted ranking system for green bonds. If the manager is concerned about a particular issuer’s ability to manage climate risk, the manager might limit the investment in that issuer’s debt to shorter maturities, but that would not apply to all bonds in the portfolio.