More ETH-BTC spread games. This allows the BTC dollar price to absorb liquidity without price rising. Textbook price manipulation. This is on a sovereign or central bank level. Market making by institutions is a critical component to understand bitcoin. 
Discussion
This trade in particular was ~3000eth converted to bitcoin which essentially creates a -150 coin short to put a cap on price.
If you have infinite dollars and infinite ability to create ETH - both of which are entirely possible. You can control the dollar price of #Bitcoin.