This paper considers the surprising, tentative emergence of the London Metal Exchange as a quasi-labour regulator following persistent scandals over cobalt mined by child labour in the Democratic Republic of the Congo (DRC). It argues that this case offers us a useful window into the limits to financialization. The ‘financialization’ of cobalt here refers to the process by which cobalt has come to be traded as a speculative asset. Such processes have often been understood in terms of a ‘divorcing’ of value from the underlying material form. The persistence of controversies around child labour and cobalt highlights clearly how fraught a process any such divorce is. Theoretically, the paper develops these arguments through engagements with Marxian and science and technology studies (STS) literatures on commodification.