Stockmarket swings and Twitter fights hackers

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Japan's Nikkei leads the downward march of stock markets. We assess the state of play as exchanges open for another day's trading across Asia. Africa's richest man tells the BBC he's investing another five billion dollars across the continent, in what he says is a vote of confidence in Africa's economic potential. And Twitter ups its security after a series of high profile hacks. To discuss the day's business news and issues, we're joined in Singapore by David Kuo of the Motley Fool financial website and in the US by Peter Morici, Professor of International Business at the University of Maryland.