Various financial crises in the past have shown how difficult it is for investors to correctly assess the risks of their investments. Rating agencies developed to support investors and improve risk assessment. With the financial crisis commencing in 2007, it became clear that potential help from external parties is an important factor for a rating. Important questions that arise are: How are rating agencies taking possible external help into account and how does this affect the overall assessment? This paper looks at the three leading rating agencies, as they share a large part of the market among themselves. Government, bank and corporate bonds are being analysed. The central question concerns the difference between stand-alone and all-in rating for governments, banks and corporate bonds. Moreover, which influencing factors play a decisive role according to rating agencies and which of these have actually been proven in practice. A stand-alone rating is an evaluation of the intrinsic strengths of a company, a bank or a state. The all-in rating takes potential external influences or assistance into account. At the beginning of this thesis, the fundamentals of bonds and bond investments are presented. In addition, the various rating scales are presented. Subsequently, different forms of liability, which are common in Austria, are discussed, as they form a significant factor in potential external support. This is followed by a presentation of the rating development of governments, banks and corporate bonds. The rating methodology of the agencies and the influencing factors they acknowledge form another part of this paper. Current studies are discussed for all bond types, to show which influencing factors are used in practice. The final part of this thesis is formed by a thorough comparison of rating methodologies and a concluding summary of the discussed topic.