Abstract: A method and system for speculatively sourcing cache memory data within a multiprocessor data-processing system is disclosed. In accordance with the method and system of the present invention, the data-processing system has multiple processing units, each of the processing units including at least one cache memory. In response to a request for data by a first processing unit within the data-processing system, an intervention response is issued from a second processing unit within the data-processing system that contains the requested data. A system bus is then requested for sourcing the requested data from a cache memory within the second processing unit before a combined response from all the processing units returns to the second processing unit.