Tyler Cowen looks at the massive scale of ECB bond buying and asks

There is a longer discussion here.  One way to read this is: “That’s not yet a lot.”  Another is: “Oh my goodness, they’ve already been doing quite a bit.”  Another is: “Lots of buying without a credible signal of future intent isn’t worth a whole lot.” I would stress the point that credible long-run signals don’t exist for Europe right now.  No one knows what “the game” will be like a year now, or less.  That makes all possible solutions harder to pull off, since announcements can be shrugged off as idle chatter.

My obvious position is that you can buy all the bonds you want and it means less than a promise to buy bonds.

More importantly, such a promise cannot be dismissed as idle chatter.

The thing many economists are missing in this whole discussion of Europe, bond prices and the like is an understanding of the motives of bond traders.

Ultimately bond traders are looking to make money. In the short term you might be looking to support a liquidity position or something, but at the end of the day everyone is looking to increase profitability.

If the ECB stands ready to buy bonds at par for example, then how can it possibly be profit maximizing to sell bonds at below par? It doesn’t matter what the fundamentals are or what the long run is or any of that. So long as you are fully confident that tomorrow you can sell your bond to the ECB at par, it is not sensible to sell it below par today.

This means interest rates on Sovereign Debt collapse if the ECB stands ready to trade.

Now, someone could come in and attempt to break the ECB. That is you could say to yourself: I don’t think the ECB really means it. They will fold if they are required to buy more than X bonds.

Then you attempt to short sell them X+1 bonds so that they will break, the price of the bonds will collapse and you can rake in a ton of money. This is a fairly high stakes game and the ECB is very large, so its not clear who will play it.

More importantly, while I definitely see the ECB as the type of institution that would dither while Europe burned and don’t at all see them as the type of institution that would give in to a speculative attack.

I feel pretty confident that they would double down against the speculator and ruin him or her as a matter of principle. Moreover, anyone who is going to loan you the bonds for this attack has got to be worried that the ECB is going to ruin you.

So, I find it unlikely that an attack will be successful.