Could be a lot of things. Perhaps Kraken moving funds in preparation for the MtGox proceedings.
I went back and checked some of the other historical spikes in BDD. They tended to correlate to spikes upwards, not downwards.
(Dec 13, Mar-Apr 14).
I hope we learn more details around this.
There is taint from here (2 yr old though)
https://blockchain.info/address/1BBqjKsYuLEUE9Y5WzdbzCtYzCiQgHqtPNI don't know so *shrug*
Gox coins is best guess right now i think
How odd. They went into the wallet April 9th.. the day of the MtGox lag price crash..
Maybe this is a stoploss? Price is approaching the original buying price?
this guy/girl just send 101 btc of the 70k coins - the rest is still in the wallet ?!
finally someone who gets it

You're underthinking it. It's completely possible the guy just decided, "Today's a good day to move all of my coins to a new wallet", but that makes absolutely no sense.
Maybe it was a sale to someone who wanted a ton of coins with no slippage? Maybe they're preparing to sell them on an exchange? Who knows.. but "they sent them to a new wallet and then spend 100" makes no sense.