Loading the player... Covariance is a measure of the degree to which returns on two risky assets move in tandem. A positive covariance means that asset returns move together, while a negative covariance means returns move inversely.
1. Rotterdam (the Netherlands) This Dutch harbor was the largest in the world, until Shanghai and Singapore grew even larger in 1986. This satellite photo gives an indication of the size of the Port of Rotterdam. (Image via Mannlines) About an hour and a half to the south of Rotterdam is Antwerp, the largest port in Belgium.
China has opened the worldâs longest sea bridge, a 26.4 mile-long structure that could easily span the English Channel. Stretching across the wide blue waters of Jiaozhou bay, the vast Y-shaped bridge connects the booming Northern port city of Qingdao with an airport built on a nearby island and the industrial suburb of Huangdao.