Two Stocks in 'Different' Sectors on Your Screener Might Actually Be the Same Bet. Here's How IDX-IC Classification Works
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5 min read
You sort your IDX holdings by sector to spread your risk. United Tractors (UNTR) sits under "Industrials." Bukit Asam (PTBA) sits under "Energy." Different sectors, so you assume they are different bets. Then, in the nine months through September 2025, PTBA's net profit dropped 56.84% as coal prices fell, and UNTR's own coal-mining revenue slid the same year on the same weak coal prices. Two "different sector" holdings, one bad stretch, for the same reason.
That is not a screener bug. It is what IDX-IC classification (IDX Industrial Classification: the system the exchange uses to sort every listed company into a sector) actually measures, and it is not the same thing as "what moves this stock's price."
IDX-IC is the classification system the Indonesia Stock Exchange has used since 25 January 2021, when it replaced an older, shallower system called JASICA. JASICA sorted companies into 9 sectors and 56 sub-sectors. IDX-IC goes four levels deep: 12 sectors, then 35 sub-sectors, then 69 industries, then 130 sub-industries, according to the exchange's own launch documentation, reported at the time by Kompas.com and Bisnis.com.
The 12 sectors are Energy, Basic Materials, Industrials, Consumer Non-Cyclicals, Consumer Cyclicals, Healthcare, Financials, Properties & Real Estate, Technology, Infrastructures, Transportation & Logistics, and Listed Investment Products.
Every listed company is placed at every one of those four levels, but only once. IDX-IC assigns each company to a single sector, sub-sector, industry and sub-industry based on what is judged its primary line of business. For a company with one clear business, that single label works fine. For a diversified conglomerate, it can flatten a lot of what actually drives the stock.
UNTR sits in Sector C, Perindustrian (Industrials), filed all the way down to the sub-industry "Construction Machinery & Heavy Vehicles." PTBA sits in Sector A, Energi (Energy), filed down to "Coal Production." That is a genuine difference at the top level, the broadest one IDX-IC has. If you screened by sector alone, these two would never show up in the same bucket.
Here is UNTR's own revenue by business line for full-year 2025, as reported in its FY2025 results (unitedtractors.com, and Kompas.com, 27 February 2026):
| Business line | FY2025 revenue |
|---|---|
| Mining Contracting (PAMA) | Rp54.1 trillion |
| Construction Machinery | Rp36.6 trillion |
| Coal Mining | Rp24.2 trillion |
| Gold & Other Mineral Mining | Rp14.0 trillion |
Construction Machinery, the business that actually earns UNTR its "Industrials" label, made up only about 28% of that revenue. The rest came from mining contracting for coal miners, UNTR's own coal mines, and its gold mining unit (through PT Agincourt Resources, which runs the Martabe mine). UNTR also holds nickel mining and processing assets in Southeast Sulawesi, acquired in 2023 through PT Stargate Pacific Resources. None of coal, gold or nickel appears anywhere in the word "Industrials."
That mix showed up directly in the numbers. UNTR's net profit for FY2025 fell 24% year on year to Rp14.8 trillion, which the company attributed to weaker mining-contracting and coal contributions, only partly offset by higher gold prices. Over the same period, PTBA, the "pure play" coal miner in a different sector entirely, saw its own 9M2025 net profit fall 56.84% to Rp1.39 trillion, a drop it tied directly to a 22% fall in the Newcastle coal price index and a 16% fall in Indonesia's own ICI-3 coal benchmark (Databoks/Katadata, citing PTBA's disclosures).
Different sector tags. The same coal-price cycle hit both.
This is not IDX-IC being wrong. A classification system groups companies by what they primarily do, so an equipment maker and a coal miner file into different sectors even when the equipment maker also owns coal mines. That is a reasonable way to sort businesses. It was never built to be a risk-exposure map, and treating it like one is the mistake, not the classification itself.
A conglomerate like UNTR earns from several commodity-linked units that never surface in its single sector tag. The deeper IDX-IC levels, sub-sector, industry, sub-industry, add more detail about the primary business, but they still file a multi-segment company under one line, not a blend of everything it actually earns from.
The reverse mistake exists too. Astra Agro Lestari (AALI) and Unilever Indonesia (UNVR) both sit in Sector D, Consumer Non-Cyclicals, just in different sub-sectors. Both are exposed to the crude palm oil (CPO) price. But AALI is a plantation company that earns more when CPO prices rise, its first-half 2026 profit rose 56.5% to Rp1.09 trillion on higher CPO prices, per Bisnis.com's April 2026 coverage, while UNVR buys CPO as a raw material, so a higher CPO price squeezes its margins instead.
Same sector, same commodity, opposite direction. A sector match tells you these two share an exposure. It does not tell you whether that exposure helps or hurts either one.
Two takeaways sit on either side of the UNTR/PTBA and AALI/UNVR pairs. A shared sector does not guarantee a shared direction, and different sectors do not guarantee independent risk. The sector tag is a starting point for research, not a substitute for it.
Before assuming two holdings diversify each other because a screener sorts them into different sectors, or two holdings move together because it sorts them into the same one, check what each company's revenue actually depends on: read its segment breakdown in its latest annual report or investor presentation, not just the label. NetWort's Explore page lets you screen IDX stocks side by side on valuation, volatility and other metrics, which is a better way to spot a shared exposure than the sector column alone. The same logic behind why P/E ratios differ so much across IDX sectors applies here: the label is a rough sort, not the full picture of what actually moves the stock.