老师请问为何不选Portfolio 3?

NO.PZ2018120301000026 问题如下 Leahinforms Molly thC ha single $500 million liability e in nineyears, anshe wants SR to construa bonportfolio thearns a rateof return sufficient to poff the obligation.Mollyprovis the four US llar–nominatebonportfolios in Exhibit 1 forconsiration. Molly explains ththe portfolios consist of non-callable,investment-gra corporate angovernment bon of various maturities becausezero-coupon bon are unavailable. Basen Exhibit 1, whiof the portfolios will best immunize SR’s singleliability? A.Bonportfolio 1 B.Bonportfolio 2 C.Bonportfolio 3 CorreAnswer: is correct. In the case of a single liability, immunization is achievematching the bonportfolio’s Macaulration with the horizon te. C ha single liability of $500 million e in nine years. Portfolio 2 ha Macaulration of 8.9, whiis closer to 9 ththof either Portfolio 1 or 3. Therefore, Portfolio 2 will best immunize the portfolio against the liability. 请问这题能不能选portfolio 4？

NO.PZ2018120301000026问题如下 Leahinforms Molly thC ha single $500 million liability e in nineyears, anshe wants SR to construa bonportfolio thearns a rateof return sufficient to poff the obligation.Mollyprovis the four US llar–nominatebonportfolios in Exhibit 1 forconsiration. Molly explains ththe portfolios consist of non-callable,investment-gra corporate angovernment bon of various maturities becausezero-coupon bon are unavailable. Basen Exhibit 1, whiof the portfolios will best immunize SR’s singleliability? A.Bonportfolio 1B.Bonportfolio 2C.Bonportfolio 3 CorreAnswer: is correct. In the case of a single liability, immunization is achievematching the bonportfolio’s Macaulration with the horizon te. C ha single liability of $500 million e in nine years. Portfolio 2 ha Macaulration of 8.9, whiis closer to 9 ththof either Portfolio 1 or 3. Therefore, Portfolio 2 will best immunize the portfolio against the liability. C的到期时间是9年，4个protfolio的平均到期时间除了3都远大于9.那么这构建免疫的时候不用考虑这个因素是嘛

NO.PZ2018120301000026 问题如下 Leahinforms Molly thC ha single $500 million liability e in nineyears, anshe wants SR to construa bonportfolio thearns a rateof return sufficient to poff the obligation.Mollyprovis the four US llar–nominatebonportfolios in Exhibit 1 forconsiration. Molly explains ththe portfolios consist of non-callable,investment-gra corporate angovernment bon of various maturities becausezero-coupon bon are unavailable. Basen Exhibit 1, whiof the portfolios will best immunize SR’s singleliability? A.Bonportfolio 1 B.Bonportfolio 2 C.Bonportfolio 3 CorreAnswer: is correct. In the case of a single liability, immunization is achievematching the bonportfolio’s Macaulration with the horizon te. C ha single liability of $500 million e in nine years. Portfolio 2 ha Macaulration of 8.9, whiis closer to 9 ththof either Portfolio 1 or 3. Therefore, Portfolio 2 will best immunize the portfolio against the liability. market weighteration不等于portfolio ration，它又不能用来判断选择哪个portfolio去match，那么market weighteration的应用是啥？

NO.PZ2018120301000026 问题如下 Leahinforms Molly thC ha single $500 million liability e in nineyears, anshe wants SR to construa bonportfolio thearns a rateof return sufficient to poff the obligation.Mollyprovis the four US llar–nominatebonportfolios in Exhibit 1 forconsiration. Molly explains ththe portfolios consist of non-callable,investment-gra corporate angovernment bon of various maturities becausezero-coupon bon are unavailable. Basen Exhibit 1, whiof the portfolios will best immunize SR’s singleliability? A.Bonportfolio 1 B.Bonportfolio 2 C.Bonportfolio 3 CorreAnswer: is correct. In the case of a single liability, immunization is achievematching the bonportfolio’s Macaulration with the horizon te. C ha single liability of $500 million e in nine years. Portfolio 2 ha Macaulration of 8.9, whiis closer to 9 ththof either Portfolio 1 or 3. Therefore, Portfolio 2 will best immunize the portfolio against the liability. 老师好， 什么是market valueweighteration ,就是指maucalration 吗？谢谢。