Comment Everyone is missing the bigger picture! (Score 3, Informative) 147
For the sake of simplicity and readability, I'm calling these wallets A, B, C, etc.
Are you beginning to see that there's a pattern to these transactions? This latest "mysterious" transaction is but a single tree in a forest. Would anyone like to bet me that we won't see wallet D making a similar outgoing transfer sometime around August?
Allow me to suggest that wallets A, B, C, and D are likely all owned by the same person or entity... if that is the case, then what we actually see is that they've spent 5000 BTC on each of those dates. In fact it's entirely possible that they also own wallets X, Y, and Z, and merely wanted an additional layer of transactions to help insulate themselves from when those bitcoins were actually spent.