IHSG vs Southeast Asia Stock Market Returns: Indonesia Is Losing Badly in 2026
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5 min read
If your Indonesian stock portfolio has had a rough 2026, you have probably told yourself it is a global problem, not a local one. Markets everywhere have been volatile this year, so a falling IHSG (Indeks Harga Saham Gabungan, Indonesia's main stock index) should not be surprising.
Except it is not what happened next door. While the IHSG fell close to 28% between the start of 2026 and the end of July, Singapore's stock market climbed more than 21%, Thailand's climbed almost 29%, and Malaysia's edged up too. This is not a regional slump. Indonesia is the outlier.
Here is the same comparison every serious investor should run before assuming their own market's problems are shared: the year-to-date price return (index points only, not including dividends) for four major Southeast Asian stock indexes, from their last trading day of 2025 to their last trading day of July 2026.
| Index | Country | 31 Dec 2025 close | 31 Jul 2026 close | YTD change |
|---|---|---|---|---|
| IHSG | Indonesia | 8,646.94 | 6,236.13 | −27.9% |
| SET Index | Thailand | 1,259.67 | 1,623.64 | +28.9% |
| Straits Times Index (STI) | Singapore | 4,646.21 | 5,628.50 | +21.1% |
| FBM KLCI | Malaysia | 1,680.11 | 1,724.90 | +2.7% |
IHSG: Antara News, 30 December 2025 close, and Kompas.com, 31 July 2026 close. SET Index: The Stock Exchange of Thailand's own December and full-year 2025 market report, and Kaohoon International's 31 July 2026 market roundup. STI: Securities Investors Association Singapore (SIAS), December 2025 Monthly Market Wrap and SIAS, July 2026 Monthly Market Wrap. FBM KLCI: The Star, 31 December 2025 close, and BusinessToday, 31 July 2026 close. Percentage changes are self-derived from these sourced, dated closing levels.
Even Malaysia, the closest thing to a laggard among Indonesia's neighbors this year, still finished in positive territory at +2.7%, while the IHSG was deep in the red.
If 2026 were a bad year for emerging Southeast Asian markets in general, you would expect the SET, STI and KLCI to be falling too. They are not. That points to something specific happening inside Indonesia rather than a shared regional or global shock.
Some of that story is already documented in NetWort's own reporting this year: a rupiah crisis driven by a balance-of-payments deficit, an oil price shock, and a series of Bank Indonesia rate hikes to defend the currency, the same drivers behind the IHSG's steep early-2026 slide covered in our look at how the DXY dollar index and the IHSG have actually moved together. None of those pressures are unique to Indonesia's neighbors in the same way.
Everything above is a local-currency price index comparison, index points in each country's own currency, so it does not yet account for what happened to the rupiah, ringgit, baht and Singapore dollar themselves over the same window.
For Indonesia specifically, that adjustment makes the picture worse, not better. The rupiah weakened from Rp16,737 per US dollar on 31 December 2025 (Liputan6) to Rp18,078 per US dollar on 31 July 2026 (valutafx.com), a depreciation of about 8.0%. Stack that on top of the IHSG's own 27.9% local-currency decline, and a US-dollar-based investor holding the same Indonesian portfolio was down roughly 33% over the period, self-derived from these two sourced exchange rates and the IHSG levels above, not a separately cited figure.
This piece does not attempt the same currency-adjusted calculation for Thailand, Singapore and Malaysia, since a reliable, consistently dated exchange rate for all three could not be confirmed at draft time. But the direction of the Indonesia-specific finding is clear either way: whatever gap exists between the IHSG and its neighbors in local-currency terms, it does not shrink once the rupiah's own weakness is added in for a foreign investor. It only grows.
None of this means Indonesian stocks are a bad long-term holding, or that Thailand and Singapore will keep outperforming for the rest of 2026. Index levels move fast, and a strong first seven months can still turn. But it does mean one specific, common assumption is wrong: that a bad year for the IHSG reflects a bad year for Southeast Asian equities generally. It has not. The IHSG's problems in 2026 look domestic, not regional.
If you hold Indonesian equities alongside anything else in the region, or you are trying to work out whether your own portfolio's underperformance is a market-wide condition or specific to your holdings, that distinction is worth checking before you decide what, if anything, to do about it.
Open the Market page in NetWort to see current IDX sector and stock-level moves rather than relying on the headline "IHSG is down" figure alone. Bank Central Asia (BBCA), the IHSG's single largest constituent, is one of the names most responsible for the index's swings; see its own price history on the BBCA asset page. This comparison pairs well with how to judge whether your own return is actually good, once you pick the right benchmark, the same benchmarking question this article just applied at the level of an entire region.