A local commercial bank staff receives bricks of dong bank notes from a customer in Hanoi. - 

Let's turn to Vietnam -- where the stock market has been on a rollercoaster ride for a week.

That's because one of the country's most powerful bankers -- was arrested last Monday, for undisclosed financial crimes.

Nga Pham is with the BBC's Vietnam Service explains in the audio above how one extremely well-connected guy can cause all this market turmoil.

"The trust in the Vietnamese banking industry is not very high," Pham says.

Follow Jeremy Hobson at @jeremyhobson