Before revision:  In addition, the algebraic connectivity of the equity securities network, taken as a measure for the robustness of financial markets, drops already sharply well ahead of the 2008 financial crisis .
After revision:  In addition, the algebraic connectivity of the equity securities network, taken as a measure for the robustness of financial markets, drops already sharply well ahead of the proliferation of several over-the-counter-traded financial derivatives, most prominently credit default swaps, enabling one to detect potentially dangerous levels of market interdependence and systemic risk .