Abstract: By collecting the yield data of Shanghai and Shenzhen A shares from 2002 to 2012， this paper constructs the stock crosscorrelation networks of pre， in and postnontradable shares reform periods and empirically studies the networks' structural stability under perturbations. The results demonstrate that from the perspective of yield synchronization and maximal eigenvalue of correlation matrix， the networks' structural stability is not changed in the process of the nontradable shares reform， and is strengthened after this reform. Moreover， from the perspective of the networks' basic topological features， the reform does not significantly affect the stability of network average shortest path length and average clustering coefficient under perturbations. This study might provide guidance to portfolio investment and risk management in the stock markets.

Key words: stock crosscorrelation network, correlation mode, stability, nontradable shares reform