下面是ECB对SMP的定义：
Securities Markets Programme
Interventions by the Eurosystem in public and private debt securities markets in the euro area to ensure depth and liquidity in those market segments that are dysfunctional. The objective is to restore an appropriate monetary policy transmission mechanism, and thus the effective conduct of monetary policy oriented towards price stability in the medium term. The impact of these interventions is sterilised through specific operations to re-absorb the liquidity injected and thereby ensure that the monetary policy stance is not affected.

SMP最早是在10年5月推出的，该计划允许ECB和各国央行(17 NCBs)从公开市场购买ZF债券从而降低ZF的融资成本。事实上ECB是不被允许直接去fund goverment的，所以要在公开市场上从银行和其他bond holders手里买债券. 注意定义里最后提到了sterilization,这是因为ECB不想让SMP被误解为QE，因而要冲销掉SMP产生的流动性,通常这个流动性是通过从MFIs(Monetary and Financial Institutions)借款冲销掉的。现在SMP的总量在211.5bn (http://www.ecb.europa.eu/mopo/im ... mmunication.en.html)，在ECB资产负债表里只占很小的一部分。
当然，这个program也经受了市场的多方质疑，有人说这已经是credit policy,超越了monetary policy的范畴，影响了ECB的独立性。也有人说stelization并不有效，等等。
在今年2月的LTRO推出以后SMP就被搁置了. 不过最近Draghi提到欧元区货币政策传导机制失效（具体机制可以看这里：http://wallstreetcn.com/node/16623）,加之意大利西班牙国债的bid/offer spread上升，再结合SMP定义中的"The objective is to restore an appropriate monetary policy transmission mechanism"，有不少人预期欧洲央行将重启SMP。