本篇論文目的在於研究CDS、債券、股票、信評機構、股票分析師這五個市場之間的關連性。由於剛剛經歷了金融海嘯，我們選擇研究這個期間內這五市場相對變化關係。實證結果發現股票市場在於事件日對於提升評等會有正報酬，對於降低評等則有負報酬。至於CDS市場則是在事件日之前就會提早反應，而且提升評等會有負報酬、降低評等有正報酬。這不但符合直覺而且也證實了CDS市場相較於其他市場具有更多內部資訊。CDS市場早在評等被改變前就會提早反應這些資訊。至於債券市場，我們實證發現似乎與分析師及信評機構的評等改變是沒有太大的關連性的。 This paper is aimed to explore the relationships among credit default swap (CDS) markets, stock markets, bond markets, rating agency and analysts‟ recommendations over the past three years. After financial crisis, it is interesting for study the relate changes with each markets when credit ratings or analysts‟ recommendations announced. We show that in event day stock market will have significant positive returns with upgrades and significant negative returns with downgrades, the CDS market will response the revision before the event day and have significant positive returns with downgrades after announce day. This is consistent with our assumption that CDS market includes more internal information. As for the bond market seem to be unrelated with analysts‟ recommendation revisions.