The impact of Credit Rating Announcements on Credit Default Swap Spreads - An empirical study of the North American Credit Default Swap Market before, during and after the global financial crisis of 2008-2009

A Credit Default Swap spread is a reliable measure of credit risk as it is the compensation demanded by a party to bear this risk. Officially, credit risk is denoted as credit ratings announced by credit rating agencies. Since rating announcements contain information regarding credit risk, the market should incorporate this new information into the CDS spread. The aim of this study is to investigate if the CDS spread reacts differently to credit rating announcements during periods of global financial distress than under relative financial stability. The study covers a period between November 26, 2004 to November 13, 2014. By conducting an event study, 300 679 daily credit default swap spreads and 370 Moody´s credit rating events from 120 entities in the North American credit default swap market are analyzed over three time periods: (1) prior to the global Sub-prime crisis of 2008-2009, (2) during the crisis and (3) after the crisis. Specifically, the announcement types, upgrade, possible upgrade, downgrade and possible downgrade are examined. On the aggregated level, all announcement types show a significant impact on the spread at the actual event day, while only negative announcements show anticipation. Combining the before and after crisis period, all event types except for downgrades show significance at the event day and no announcements display significant anticipation. During the crisis negative announcements show significant magnified anticipation and total reaction, while positive events lose its impact and significance. Lastly, after the crisis, Moody’s ratings announcements, both aggregated positive and negative announcements lose some of its impact magnitude compared to before the crisis. In sum, our findings propose that the impact of rating announcements depend on the underlying market conditions

How Many and What Types of SPARQL Queries can be Answered through Zero-Knowledge Link Traversal?

The current de-facto way to query the Web of Data is through the SPARQL protocol, where a client sends queries to a server through a SPARQL endpoint. Contrary to an HTTP server, providing and maintaining a robust and reliable endpoint requires a significant effort that not all publishers are willing or able to make. An alternative query evaluation method is through link traversal, where a query is answered by dereferencing online web resources (URIs) at real time. While several approaches for such a lookup-based query evaluation method have been proposed, there exists no analysis of the types (patterns) of queries that can be directly answered on the live Web, without accessing local or remote endpoints and without a-priori knowledge of available data sources. In this paper, we first provide a method for checking if a SPARQL query (to be evaluated on a SPARQL endpoint) can be answered through zero-knowledge link traversal (without accessing the endpoint), and analyse a large corpus of real SPARQL query logs for finding the frequency and distribution of answerable and non-answerable query patterns. Subsequently, we provide an algorithm for transforming answerable queries to SPARQL-LD queries that bypass the endpoints. We report experimental results about the efficiency of the transformed queries and discuss the benefits and the limitations of this query evaluation method.Comment: Preprint of paper accepted for publication in the 34th ACM/SIGAPP Symposium On Applied Computing (SAC 2019

Efter sälj kommer solsken – eller? En empirisk studie av buyout-aktörers bestående värdeskapande i Sverige.

Syfte: Författarna ämnar med denna studie att undersöka hur buyout-aktörers portföljbolag presterar efter avyttring. Studien ämnar utreda prestationen genom att studera finansiella nyckeltal kopplade till operativt värdeskapande. Metod: En kvantitativ metod i form av en eventstudie med deduktiv ansats. Värdeutvecklingen efter buyout-aktörers utträde ur portföljbolag studeras under eventfönstret efter avyttring för att undersöka om över- eller underprestation sker mot ett framtaget branschsnitt. Slutligen görs flertalet statistiska tester för att urskilja eventuella signifikanta skillnader. Teoretiskt perspektiv: Med avstamp i den deduktiva metoden utgår studien från tidigare forskares teorier värdeskapande i buyout-bolag och möjliggör jämförelser med tidigare forskning och uppsatser genom applicering av metodval från dessa. Empiri: Data består av räkenskaper från portföljbolag ägda av medlemmar hos SVCA och är avyttrade mellan år 2004-2010. Detta tillsammans med räkenskaper från branschkonkurrenter samlats in för att undersöka värdeutveckling under det efterföljande eventfönstret. Resultat: Studien visar på statistiskt signifikant överprestation i portföljbolag gentemot ett branschsnitt i de operationella nyckeltalen EBITDA-marginal samt avkastning på operativt kapital under eventfönstrets första period. Avseende förändring i nettoomsättning kunde inte någon överprestation säkerställas. Detta kunde inte heller göras för EBITDA-marginal eller avkastning på operativt kapital för kvarvarande perioder av eventfönstret. Under hela den undersökta perioden om tre år påvisades ingen signifikant över- eller underprestation avseende något av de tre nyckeltalen

TNM staging with FDG-PET/CT in patients with primary head and neck cancer

Purpose: PET/CT, PET+CT, and CT were compared concerning accuracies in TNM staging and malignancy detection in head and neck cancer. The impact of PET/CT compared to the other imaging modalities on therapy management was assessed. Materials and methods: Fifty-five patients with suspected head and neck primary cancer underwent whole-body FDG-PET/CT. PET/CT and PET+CT were evaluated by a nuclear medicine physician and a radiologist; CT was evaluated by two radiologists, PET by two nuclear physicians. Histopathology served as the standard of reference. Differences between the staging modalities were tested for statistical significance by McNemar's test. Results: Overall TNM-staging and T-staging with PET/CT were more accurate than PET+CT and CT alone (p < 0.05). PET/CT was marginally more accurate than CT alone in N-staging (p = 0.04); no statistically significant difference was found when compared to PET+CT for N-staging. PET/CT altered further treatment in 13 patients compared to CT only and in 7 patients compared to PET+CT. Conclusion: Combined PET/CT proved to be partly more accurate in assessing the overall TNM-stage than CT and PET+CT. These results were based on a higher accuracy concerning the T-stage, mainly in patients with metallic implants and marginally the N-stage. Therapy decisions have been influenced in a substantial number of patients. PET/CT might be considered as a first line diagnostic tool in patients with suspected primary head and neck cance