嗨,从没放弃的小努力你好:
derivative overlay基础班讲义中的例题(reading19)
该例题中描述the duration drift has arisen because of a widening spread between corporate and government bond yields as interest rate have come down.The lower yields on government bonds have increased the modified durations relative to corporate debt liabilities.
请问老师关于这两句话中的利率变化对spread和duration的理解
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the duration drift has arisen because of a widening spread between corporate and government bond yields as interest rate have come down.
这句话的意思是面对基准利率下降,期初做到BPVA=BPVL可能不在成立,duration drift(漂移)使得二者不相等。原因是:
基准利率与spread变动方向相反(最后一个reading讲credit strategy会讲到这个结论),根据yc=yb+spread,国债的折现率是yb,公司债的折现率是yc,基准利率下降,则spread会上升,使得|△yc|<|△yb|,此时yc-yb变大,也就是widen spread,△yc<△yb使得△BPV不一定相等,产生duration drift,这个风险是spread risk,就是由于国债与公司债相对基准利率的spread不同导致的。
The lower yields on government bonds have increased the modified durations relative to corporate debt liabilities.
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这句话的意思是基准利率下降,且|△yc|<|△yb|,则△BPVL>△BPVA,负债是国债,资产是公司债,所以最终的BPVL>BPVA。这句话说的不准确,不是increased the modified duration,而应该是money duration或者BPV。
这两句话描述的就是spread risk,spread risk就是资产与负债的债券类型不一样,导致基准利率变动后,BPV不再相等,产生duration gap,此时,就需要用derivative overlay了,同学掌握这个原理即可。
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