If the ECB commits to buying N bn €-Mark's worth of bonds, then "the market" will simply short N bn + 1 €-Mark's worth of bonds, and laugh all the way to the bank.

ECB has introduced an upper limit of €20bn per week for SMP interventions

According to Frankfurter Allgemeine Zeitung, the ECB governing council has introduced an upper limit of €20bn the central bank can spend per week to help ailing euro countries to stabilize the spreads on their government bonds. This move is interesting in the sense that the market expectations are that with the arrival of Mario Draghi and the intensification of the crisis the ECB would go the other way and loosen its limits of the program. The paper, however, argues that there is a growing scepticism among the governing council's members about the program which has resulted in lowering the weekly ceiling from a previously higher figure to €20bn. According to FAZ discusses at each of its bimonthly meetings the SMP and sets a ceiling for the coming two weeks. Whether the €20bn ceiling was maintained at yesterday's governing council meeting is unclear. According to the ECB's official SMP figures it spend only €4.5bn last week, much less than the markets had expected.