Simon English: Who is mastermind pulling the strings?

Outlook Stock-market shenanigans, grand conspiracy theories department. Here's what happened (so says this bloke in the pub who is never wrong. Hardly). On Monday, someone really, really big, surveyed the week before them and shorted global stock markets. Then they put the rumour around that the Greece deal was close to failure, knowing otherwise.

On Tuesday those markets fell. On Wednesday they bought back in heavily with their gains from the big short. On Thursday they enjoyed a rally in the morning and started selling as Greek optimism rose.

Today they are on a (metaphorical or real) plane to the Bahamas.

Who was it?