I've just worked out, that was a 115 BTC buy (Mintpal).
There have been a hell of a lot of these huge buys at all time highs the last few days. Basically someone bought the entire 15 sellwall in 1 order. That would usually take hours or days to eat through, especially after a big rise like we've just had.
What's going on ? Why are people ploughing 115 BTC into it at the all time high ? They also did this at the last peak of around 8 I think it was.
Negative Theories:
- it's the NSA planning to monopolise the masternode network
Positive Theories:
- it's bitcoin whales hedging themselves against the new wave of demand for anonymous transaction blockchains
It's make your mind up time

Evan says he plans to release Ring Signatures and I2P to further anonymize Darkcoin so anonymity won't only rely on the Masternodes, so I highly, heavily doubt it'd be the NSA...
It's more than likely different sets of "whales" or people with generally large amounts of BTC, that are interested in Darkcoin and believe that it can reach much higher prices. After all, we are "early" on in Darkcoin, huge interest really began happening about a week ago, and the price could reach much much higher than this.