JAKARTA — Indonesia's stock market experienced significant volatility during Tuesday's trading session (September 29, 2026) after the Ministry of Energy and Mineral Resources (ESDM) officially issued strict regulations that alter the operational landscape for mining companies. The new policy, outlined in ESDM Ministerial Decree No. 365.K/MB.01/MEM.B/2026, mandates that all mining business license holders must prioritize local mining service companies in their operational areas, rather than relying on their own subsidiaries or affiliates.
According to CNBC Indonesia, the rule, signed by ESDM Minister Bahlil Lahadalia, aims to provide legal certainty while stimulating the local economy in areas surrounding mining sites. The impact was immediately felt on the Indonesia Stock Exchange (IDX), where the energy sector index (IDXENERGY) fell 2.09% as of 09:35 WIB.
Direct Impact on Valuation and Margins
Market reaction indicates investor concern over potential declines in net profit margins for mining issuers. Several major companies recorded sharp drops:
- PT Adaro Andalan Indonesia Tbk (AADI): Plunged 5.59% to Rp10,975 per unit.
- PT Alamtri Resources Indonesia Tbk (ADRO): Dropped 5.02% to Rp2,460.
- PT Bara Jaya Energi Tbk (BIPI): Declined 4.58%.
- PT Bukit Asam Tbk (PTBA) and PT Indo Tambangraya Megah Tbk (ITMG) were also under pressure, correcting by 2.52% and 2.15%, respectively.
Prohibition Mechanism and Exceptions
The rule explicitly prohibits the involvement of subsidiaries or affiliates in the mineral and coal mining services business, whether through direct share ownership or common ultimate beneficial owners. Exceptions are granted only for national strategic projects, smelter construction, or meeting domestic needs, and must go through specific ESDM Minister approval with a maximum processing time of 14 working days.
"Mining Business License holders... are prohibited from involving subsidiaries and/or affiliates in the mineral and coal mining services business without the Minister's approval," reads the second clause of the rule, as quoted from news sources.
Strategic Implications for Investors
For quantitative investment committees, this regulation signals a policy shift from corporate efficiency to local economic inclusivity. Investors need to re-evaluate the valuation of coal issuers with a large share of internal mining services. We recommend monitoring issuers with strong local contractor networks as potential beneficiaries of this rule, while issuers with high vertical integration structures may need to adjust target prices in their valuation models.
This rule also repeals Directorate General of Mineral and Coal Regulation No. 376.K/30/DJB/2010, marking a new era of stricter and more transparent mining governance in Indonesia.