It's a question increasingly asked in market discussions, especially since the brief period of deficit drama in the UK last year - is the weight of sovereign debt too much for investors to bear? And, if not yet, is there a level of yields at which debt spirals become more likely? Marvin Loh, senior strategist on our team in the US, is back to discuss those questions, as well as to provide guidance on what to expect ahead of an upcoming Federal Reserve meeting.