Foreign Investors Sold Rp10.24 Trillion in September. Does Net Foreign Flow Push the IHSG or Follow It?
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5 min read
In September 2026, foreign investors net sold Rp10.24 trillion of Indonesian stocks. The IHSG fell 6.96% over the same month (Katadata and IDX Channel, retrieved 13 October 2026).
It is easy to read that as "foreigners sold, so the market fell." But did they push the market down, or did they sell because it was already falling? That question is the whole point of net foreign flow, and the answer is less clean than the headlines suggest.
Net foreign flow is one number. It is what foreign accounts bought, minus what they sold, in rupiah.
If the number is positive, it is a net buy. If it is negative, it is a net sell. Our earlier guide, what a foreign net sell actually measures, walks through a real day in detail. This article asks a different question: who is "foreign", and does their trading lead the market or trail it?
"Foreign" does not mean "a person with a foreign passport." In market data, it generally means an account that is registered as foreign, such as an overseas fund or a bank's overseas desk.
That has two side effects:
We could not open KSEI's or IDX's own classification rules from our research tools. So treat this as the general idea, and check the exchange's definitions if you need exact edge cases.
Here are four recent periods. Foreign money net sold in all of them. The index did not always agree.
| Period | Foreign net flow | IHSG |
|---|---|---|
| September 2026 (month) | Net sell Rp10.24 trillion | Down 6.96% |
| 28 Sep to 2 Oct 2026 (week) | Net sell Rp1.27 trillion on the Friday alone | Down 3.28% to 6,036.88 |
| 6 Oct 2026 (one day) | Net sell Rp629.87 billion | Up 1.21% |
| 9 Oct 2026 (morning session only) | Net sell Rp32.05 billion | Up 0.35% to 6,052.51 |
Sources: Bisnis.com weekly report, 3 October 2026 and Kabar Bursa market reports, 6 and 9 October 2026, via search summaries on 13 October 2026.
Notice the pattern. Over a month and a week, selling and falling went together. On single days in October, the selling continued while the index rose. Foreign selling clearly did not stop the rebound.
Often it follows. Foreign funds trim when prices drop and when risk rises. That makes the sell list a result of the fall, not only a cause.
Research on Indonesia is mixed:
We read these through search summaries, not the full papers. Monthly data also cannot tell you what happens inside a day. So the safe reading is modest: at index level and over months, flow and price move together. Whether flow came first is much harder to show.
A single stock has its own news, earnings and index changes. One fund trimming a position can look like a "foreign net sell" headline, even when the reason has nothing to do with the company.
Domestic buyers also matter. Foreign investors made up about 39% of daily trading value in the second quarter of 2026, per Katadata. Domestic accounts trade the rest, and they can absorb a lot of foreign selling.
Before you react to a net foreign flow number, ask three questions:
Think of foreign flow as a thermometer, not a steering wheel. It tells you the temperature. It does not say why.
Open the NetWort Market page. Put the index move and top movers next to any foreign flow headline you read this week. If the two tell different stories, trust the price data you can see over the headline you were told.