  Financial market is an example of complex system, which is characterized by a
highly intricate organization and the emergence of collective behavior. In this
paper, we quantify this emergent dynamics in the financial market by using
concepts of network synchronization. We consider networks constructed by the
correlation matrix of asset returns and study the time evolution of the phase
coherence among stock prices. It is verified that during financial crisis a
synchronous state emerges in the system, defining the market's direction.
Furthermore, the paper proposes a statistical regression model able to identify
the topological features that mostly influence such an emergence. The
coefficients of the proposed model indicate that the average shortest path
length is the measurement most related to network synchronization. Therefore,
during economic crisis, the stock prices present a similar evolution, which
tends to shorten the distances between stocks, indication a collective
dynamics.
