Greece Financial Economy

I want to understand how one nation is deciding all the financial markets of the world. Greece is bankrupt and every country is giving suggestions to make it overcome with the situation. Whenever I see  news of stock markets up or down, the reason given is "Greece". How one country can affect so much?

I know that whole European economy is affected but why every nation is focusing on Greece. Today markets are down and the reason given is "Asian markets slip on Greece". Now when bailout packages were announced for Greece, the markets were up. Somebody please help me in finding out that why only Greece is deciding world's financial markets. Thanks!!

Now I become author

Today, I have been invited to be an author for somebody's blog. The person has given me rights to write on his blog. But the real problem that I am facing is when I do not get time to update my blog (though I try my best), how can I write for other's blog. I am still thinking of taking this opportunity. I know at last I will decide to give it a try and then see how it goes. But I have to think of different topics. The blog is mostly about financial markets related to world economy, so I have to do my homework before I start.

I have to think about topics which are anticipated in future. This is very important for an writer to think about subject well in advance that have the potential to be a big news tomorrow.

So guys wish me luck!!