Distributed computing is a well-known approach to perform
computationally intensive tasks. A problem inherent to this approach is the allocation of tasks to machines. This problem can be successfully addressed with a market mechanism. The article resents a comparison between two market mechanisms for an agent-based trading platform for computational resources. The platform consists of the following agents: (A) management agents (the directory facilitator, the controller agent, the account agent, and the bank agent), (B) client agents, and (C) one mediator agent. The market mechanisms used were an unmediated one, Contract Net, and a mediated one, the sealed bid, periodic, uniform-price, double auction. Experiments showed that overhead and gain were quite similar for the two market mechanisms. Regarding scalability β a highly important factor for large distributed projects β the auction scored clearly better than Contract Net.