The coins had been sitting in the wallet since April 2015, when the price of Bitcoin was in the mid-$200 range. Today, a single Bitcoin is worth around $13,800.
The holdings predate the Bitcoin Cash hard fork, meaning the address owner was also entitled to 69,370 BCH (worth a cool $16.8 million); it was the 18th-largest Bitcoin Cash wallet until those holdings were moved today as well.
The owner of the address is unknown, but hackers have been trying to get into the wallet for years using a file that purportedly held its private keys. Unfortunately for them, the password and file type made it difficult to access. No one had managed to do so in years.
Looks like someone figured it out. Or its owner wised up and moved the coins to a wallet that isn't being traded around on the dark web.
[Editor's note: This article has been updated with more information.]