Although some have called the ECB’s choice to buy asset-backed securities (ABSs) rather than government bonds "QE-lite", Tony Yates at Bristol University says this might actually prove more effective than buying government bonds. This is because government bonds are a close substitute for cash, and so conventional QE means merely swapping one safe asset for another, which limits its effectiveness. However, to the extent that ABSs are less like government bonds and more like corporate bonds, buying them should do more to reduce corporate bond yields and hence companies’ borrowing costs. This should raise capital spending by more than the same quantity of purchases of government bonds would.
That said, we cannot be confident of QE’s stimulative effect. We don't know how much of it the ECB will do - although ECB president Mario Draghi promised "sizeable" buying - nor do we know which ABSs it will buy; to the extent that it buys better quality ones, its impact will be lessened.