Sistem pemberitahuan merger yang diterapkan di Indonesia saat ini, berdasarkan Undang - Undang No.5 Tahun 1999 menganut Post-Merger Notification System atau notifikasi yang dilakukan setelah badan usaha melakukan merger. Badan usaha wajib melaporkan kepada Komisi Pengawas Persaingan Usaha selambat-lambatnya 30 hari sejak tanggal penggabungan, peleburan, atau pengambilalihan berlaku efektif secara hukum. Post-Merger notification justru menimbulkan ketidakefektifan dalam transaksi merger dan menimbulkan ketidakpastian bagi pelaku usaha. Ketidakefektifan dalam pemberitahuan akan menimbulkan masalah problematic dalam merger dan memberikan dampak negative pada pelaku usaha. Post Merger notification yang dianut oleh Indonesia memiliki berbagai kelemahan, sehingga perlu dipertimbangkan untuk dirubah menjadi Pre-merger Notification. Berdasarkan hal tersebut, artikel ini menunjukkan urgensi perubahan sistem Post-merger Notification menjadi Pre-Merger Notification sebagai upaya pencegahan praktik monopoli. Penelitian ini mengggunakan pendekatan hukum.

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The merger notification system currently implemented in Indonesia, based on Law No. 5 of 1999, adheres to the Post Merger Notification System or notification that is carried out after a business entity merges. Business entities are required to report to the Commission for the Supervision of Business Competition no later than 30 days from the legally effective date of the merger, consolidation or acquisition. Post Merger notification creates ineffectiveness in merger transactions and creates uncertainty for business actors. Ineffective notification will cause problematic problems in mergers and have a negative impact on business actors. Post Merger notification adopted by Indonesia has various weaknesses, so it needs to be considered to be changed to Premerger Notification. Based on this, this article shows the urgency of changing the Post-merger Notification system to Pre- Merger Notification as an effort to prevent monopolistic practices. This research uses a legal approach.