Systemic risk is a much broader concept implying probability of sudden disruption to a large part of the financial system, reflected in failure of multiple institutions and freezing of markets, triggered by a common shock and propagated through interconnected exposures and correlated positions.
The ECB launched Outright Monetary Transactions (OMT) in September 2012 to make discretionary purchases of short-term sovereign bonds with a prior request by the concerned sovereigns for international assistance via the EFSF/ESM.