The definition of an ‘investment’ is a highly contentious topic in investment arbitration. A range of indicative ‘characteristics’ or binding ‘requirements’ – depending on one's interpretation – have been identified: a contribution of resources, sufficient duration, incurring a certain risk, acquiring a regular profit and return, and a contribution to the economic development of the host state. Remarkably, there is still no consensus in the case law on whether any criteria should be applied at all, or what criteria those would be, or how such criteria should be interpreted. The characteristic that has been interpreted most diversely is probably the ‘contribution to the economic development of the host state’. Some tribunals have deemed it a fundamental pillar of investment arbitration; others have not even considered it important enough to mention it. In this contribution, two of those divergent decisions will be considered more closely: the Award on Jurisdiction, a case brought based on the United Kingdom–Malaysia Bilateral Investment Treaty (BIT, 1981), 1 and the Annulment Decision in Malaysian Historical Salvors, SDN, BHD v. Malaysia. 2