The country's debt agency said the shortfall in the sale reflected worsening market nerves on European debt markets but added it would sell back the retained amount to investors on secondary debt markets and that Germany would not face a funding bottleneck.

The results compared with an average retention by the central bank of 17.83 percent at 10-year bond auctions in 2011. Data from IFR, a Thomson Reuters service, showed this to be the highest Bundesbank retention since at least July 1999.

Also, the Bundesbank (not the debt agency) routinely "retains" a fraction of all bond issues? Is that a semantic legerdemain to avoid saying it's "buying" them?

To err is of course human. But to mess things up spectacularly, we need an elite — Yanis Varoufakis