German debt sold at negative yield

How does one interpret this with all of the recent financial news.  Yesterday German state five year financial bonds were sold at negative 0.08%, with buyers holding the debt and paying for the right for repayment.  Here we hold funds in banks below the FDIC insurance level for the same reason and understand the concern, or is this indicative of a more latent fear that hovers over these supposedly robust financial markets.

We know that the German bonds were sold as liquid trading vehicles, and bought by professional investors and not seen as buy and hold paper, but for trading and hedging purposes.  That's  the only way to understand this.  Otherwise, there is big trouble on the horizon.