The outcome of one of the most volatile trading weeks in recent memory will go a long way to determining the growth of the global economy and the stability of the international financial system over the next few months. It has also become clear that the old adage ‘it\'s the economy stupid\' will once again dominate the political discourse in the build-up to next year\'s US Presidential election with Washington more divided than ever before. Equity markets across the US, Europe and Asia have been battered over the last seven days as the twin debt crises in the United States and the Eurozone tighten their stranglehold over governments and financial institutions around the world. US President Barack Obama has failed to prevent America\'s debt problems from becoming a key election theme. Brinkmanship in Washington led to Republicans and Democrats only agreeing a short-term solution to the crisis with a bill that raises the country\'s borrowing limit by $2.1 trillion over the next decade. Article continues below The credit rating agency Standard & Poor\'s decided that deal does not go far enough and, in a move that had explosive ramifications for global stock exchanges, stripped the US of its prized AAA status, downgrading it to AA+ with a negative outlook. The announcement sparked a global selloff in equities, which continued throughout the week as the Eurozone\'s sovereign crisis also came to the fore amid growing concern over the stability of financial heavyweights Spain and Italy. Staff reporter Kevin Scott takes a look back at the most tumultuous week on global equity markets since the collapse of US investment bank Lehman Brothers at the height of the global financial crisis in 2008.