According to _The Guardian_, Moolah, a cryptocurrency exchange that specialized in Dogecoin (and even sponsored a car in NASCAR racing series), headed by "Alex Green", had apparently gone bust and all the customer funds (believed to be 1.4 to 1.5 million pounds?) are gone.
Alex Green allegedly told everybody that he was previously named "Ryan Kennedy" after running several business into the ground, including Flirble (a web hosting service that ran only 2 months) and Lemon (a bitcoin mining firm that shut down in 2013), according to _The Guardian_. And because this company is also done, he's taking the money and he's gonna run.
In July 2014 "Green" and his company Moolah bought a competitor "Mintpal" after Mintpal was hacked and lost $2M worth of bitcoins. However, nobody had even apparently saw "Green" in person outside of Moolah's offices.
See _The Guardian Coverage_
The risk in virtual cryptocurrencies are unacceptably high to "normal" investors. You should avoid any and all schemes that purports to "invest" in such currencies, esp. if you're buying "mining contracts" or in firms that allegedly does so. They are likely to be Ponzi schemes.
The Consumer Finance Protection Bureau, and official US government agency, urges any victims of such fraud in the US (if the firm's in the US, or the victims' in the US) to report their problems. For those who have not been victimized, please gain better understanding
A different company, called BitCoin-Trader.Biz, had also gone bust a week ago, claiming they got hacked and that's it for them. It is actually an HYIP (i.e. Ponzi scheme)