  In the age of globalization, it is natural that the stock market of each
country is not independent form the other markets. In this case, collective
behavior could be emerged form their dependency together. This article studies
the collective behavior of a set of forty influential markets in the world
economy with the aim of exploring a global financial structure that could be
called world-stock-market network. Towards this end, we analyze the
cross-correlation matrix of the indices of these forty markets using Random
Matrix Theory (RMT). We find the degree of collective behavior among the
markets and the share of each market in their structural formation. This
finding together with the results obtained from the same calculation on four
stock markets reinforce the idea of a world financial market. Finally, we draw
the dendrogram of the cross-correlation matrix to make communities in this
abstract global market visible. The dendrogram, drawn by at least thirty
percent of correlation, shows that the world financial market comprises three
communities each of which includes stock markets with geographical proximity.
