This study analyses the "de facto" emerging intra-school competition between the Israeli Ministry of Education (MOE) and external organisations at public Israeli secondary schools by exploring science, technology, engineering, and mathematics (STEM) programmes. Given on-going privatisation processes within the education system, the participation of external organisations in schools has become significant, greatly affecting municipalities' authority and schools principals' autonomy. This case-study provides a comprehensive examination of this new form of intra-school competition and its possible impact on schools, based on in-depth interviews with school principals, representatives of STEM programmes, and officials at the MOE and a local education authority, as well as analysis of supporting documents. We show that despite its supposed regulatory role, the MOE is pushed to function as an additional player in this quasi-market, competing with external organisations and substituting its regulatory roles for additional market-player opportunities. Theoretical and empirical implications are suggested.