Provides mining services with performance specified by contract. For example, a specific level of mining capacity may be rented out for a set price for a specific duration. Mining shares provide Mining as a Service (MaaS). These break large-scale datacenter mining down to easily manageable pieces that are available in the form of shares of equipment.
Hosted mining services and Cloud Mining create systemic risk for Bitcoin because they undermine the security assumption that the control of mining power is well-distributed. If too much hashrate is consolidated in large hosting centres, an attacker is more-easily able to compromise a significant portion of it and could potentially disrupt Bitcoin or steal back their own spent money.