Why are the stock markets crashing and who is responsible? If you're invested in the stock market, if you fancy yourself as a day trader or maybe just an index funder, then maybe stop reading this article, take a look at your portfolio, scream, take half an hour to compose yourself and then come back. For the rest of you, here's a recap of what's happened since the beginning of the year. Stock markets around the world have been declining, but the last few days have been…