Doutoramento em Economia
Essays on the informational efficiency of Credit Default Swaps markets
Paulo Miguel Silva

Orientação:  Isabel Maria Pereira Viegas Vieira & Doutor Carlos Manuel Rodrigues Vieira

This thesis contributes to the strand of the financial literature on credit derivatives, in particular the credit default swaps (CDS) market. We present four inter-connected studies addressing CDS market efficiency, price discovery, informed trading and the systemic nature of the CDS market. The first study explores a specific channel through which informed traders express their views on the CDS market: mergers and acquisitions (M&A) and divestitures activities. We show that information obtained by major banks while providing these investment services is impounded by CDS rates prior to the operation announcement. The run-up to M&A announcements is characterized by greater predictability of stock returns using past CDS spread data. The second study evaluates the incremental information value of CDS open interest relative to CDS spreads using a large panel database of obligors. We find that open interest helps predict CDS rate changes and stock returns. Positive open interest growth precedes the announcement of negative earnings surprises, consistent with the notion that its predictive ability is linked to the disclosure of material information. The third study measures the impact on CDS market quality of the ban on uncovered sovereign CDS buying imposed by the European Union. Using panel data models and a difference-in-differences analysis, we find that the ban helped stabilize CDS market volatility, but was in general detrimental to overall market quality. Lastly, we investigate the determinants of open interest dynamics to uncover the channels through which CDS may endanger the financial system. Although we find information asymmetry and divergence of opinions on firms’ future performance as relevant drivers of open interest, our results indicate that systematic factors play a much greater influence. The growth of open interest for different obligors co-varies in time and is pro-cyclical. Funding costs and counterparty risk also reduce dealers’ willingness to incur inventory risk.

JEL classification: E44, G12, G01, G12, G14, G15, G19, G28

Keywords: credit default swaps, CDS, market efficiency, open interest, price discovery.