Ethereum has undergone DDOS attacks since the beginning of Devcon2, with the attacker(s) spending 10s of thousands of dollars on the attacks. One would suspect a profit motive for the attacks and shorting ETH in expectation of a price drop would be reasonable. However, no material drop in price has occurred since the attacks began. The chart below says it all:
Others have speculated that the attacker could be gaining a mining advantage using this DDOS attack.
Notable quote from the man himself:
vbuterin:
There are three incentives to attack:
Claiming all tx fees for yourself if you have a better miner (the attacker is not doing this)
Get slightly higher rewards by forcing a higher uncle rate
Get higher rewards by knocking other miners off
If this is the attacker, then they are mining empty blocks so (1) does not apply. (2) may apply; https://github.com/ethereum/EIPs/issues/100 is slated for Metropolis and should remove this incentive. (3) may also apply and is of course the greater factor. That said, the attacks are at this point not affecting the network, as the miners are all on parity; yesterday's uncle rates were barely above normal and difficulty yesterday was at an all-time high.
and from Nick Johnson:
There's really no incentive for a miner to conduct a DoS attack against the network that he's mining; even if he does take nodes offline, they'll come back on as soon as the attack is over or remediated, and as Vitalik points out, the hashrate is at an all time high.
Both the mining attack and short position attack are highly speculative, but if the the attacker(s) do have a short position outstanding, it has most likely failed to gain any value, and it has definitely not gained enough value to offset the cost of the attack.
With a 6+ month consolidation range behind the ETHUSD pair, a break one way or the other is due. A sharp drop may occur first to shake out weak hands, but if it happens, I think it will be quickly retraced and an uptrend will prevail. We shall see.