An apparatus comprising: processing circuitry to perform data processing in response to instructions, wherein in response to a vector load instruction, the processing circuitry is configured to load respective data elements of a vector value with data from respective locations of a data store, and in response to a vector store instruction, the processing circuitry is configured to store data from respective data elements of a vector value to respective locations of the data store; wherein the processing circuitry is responsive to a transaction start event to speculatively execute one or more subsequent instructions, and responsive to a transaction end event to commit speculative results of the one or more subsequent instructions speculatively executed following the transaction start event; the apparatus comprises hazard detection circuitry to detect whether an inter-element address hazard occurs between an address corresponding to data element J for an earlier vector load instruction speculatively executed following the transaction start event and an address corresponding to data element K for a later vector store instruction speculatively executed following the transaction start event, where K is different to J, and both the earlier vector load instruction and the later vector store instruction are from the same thread of instructions processed by the processing circuitry; wherein in response to detecting the inter-element address hazard, the hazard detection circuitry is configured to trigger the processing circuitry to abort further processing of the instructions subsequent to the transaction start event and prevent said speculative results being committed; comprising hazard tracking storage circuitry to store hazard tracking data for tracking addresses used for one or more earlier vector load instructions speculatively executed following the transaction start event; wherein the transaction start event comprises a transaction start instruction and the transaction end event comprises a transaction end instruction; characterized in that: the hazard detection circuitry is configured to clear the hazard tracking data in response to a transaction clear instruction executed following the transaction start event, where the transaction clear instruction is different to the transaction start instruction and the transaction end instruction. processing circuitry to perform data processing in response to instructions, wherein in response to a vector load instruction, the processing circuitry is configured to load respective data elements of a vector value with data from respective locations of a data store, and in response to a vector store instruction, the processing circuitry is configured to store data from respective data elements of a vector value to respective locations of the data store; wherein the processing circuitry is responsive to a transaction start event to speculatively execute one or more subsequent instructions, and responsive to a transaction end event to commit speculative results of the one or more subsequent instructions speculatively executed following the transaction start event; the apparatus comprises hazard detection circuitry to detect whether an inter-element address hazard occurs between an address corresponding to data element J for an earlier vector load instruction speculatively executed following the transaction start event and an address corresponding to data element K for a later vector store instruction speculatively executed following the transaction start event, where K is different to J, and both the earlier vector load instruction and the later vector store instruction are from the same thread of instructions processed by the processing circuitry; wherein in response to detecting the inter-element address hazard, the hazard detection circuitry is configured to trigger the processing circuitry to abort further processing of the instructions subsequent to the transaction start event and prevent said speculative results being committed; comprising hazard tracking storage circuitry to store hazard tracking data for tracking addresses used for one or more earlier vector load instructions speculatively executed following the transaction start event; wherein the transaction start event comprises a transaction start instruction and the transaction end event comprises a transaction end instruction; characterized in that: the hazard detection circuitry is configured to clear the hazard tracking data in response to a transaction clear instruction executed following the transaction start event, where the transaction clear instruction is different to the transaction start instruction and the transaction end instruction.