It looks to be the parent company:

"NiceHash users took to Reddit to discuss the breach and speculate on whether this heist was an inside job. The speculation fuelled by the fact that the majority owner of NiceHash is a company named H-Bit, owned by Martin Skorjanc, the father of Matjaz Skorjanc, convicted author of the Mariposa bot. The younger Skorjanc is also the CTO and co-founder of NiceHash."