Embodiments related to a hardware transactional memory (HTM). An aspect includes setting a mode register of a processor core of a computer to indicate a HTM mode. Another aspect includes executing a plurality of transactions by the processor core in the HTM mode based on the mode register. Another aspect includes determining whether a first transaction of the plurality of transactions exceeds a failure limit of the processor core in the HTM mode. Yet another aspect includes, based on determining that the first transaction exceeds the failure limit of the processor core in the HTM mode, transitioning the processor to an assisted transaction mode by setting the mode register of the processor core to indicate the assisted transaction mode.