What Actually Happens When an IDX Stock Hits Auto Reject? The Circuit Breaker Rules Explained
7 min read
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7 min read
You are watching a stock you own fall fast. Then, suddenly, the price just stops moving. Your sell order will not go through, and the last price on the screen stays frozen. Nothing you do changes it.
That is auto reject at work, one of a few different mechanisms the Indonesia Stock Exchange (IDX, or BEI in Indonesian) uses to slow trading down when prices move too far, too fast. It is not a glitch and it is not your broker's fault. It is a rule, and understanding what it actually does, and does not do, matters more than most investors realise.
Auto reject is a daily price band. On any single trading day, the IDX will not let a stock's price move above or below a set percentage of its previous closing price. Try to place an order outside that band, and the exchange's own trading system, JATS (Jakarta Automated Trading System), automatically rejects it before it ever reaches the market.
There are two sides to this band:
The size of the band depends on the stock's price, and the two sides are no longer symmetrical. Under the rules in effect since 8 April 2025, the IDX applies:
| Price range | ARA (upper limit) | ARB (lower limit) |
|---|---|---|
| Rp50 to Rp200 | 35% | 15% |
| Above Rp200 to Rp5,000 | 25% | 15% |
| Above Rp5,000 | 20% | 15% |
ARA bands per share price tier: BNI Sekuritas, effective since 4 September 2023. ARB set to a flat 15% across all price tiers, replacing the previous tiered structure, via two IDX Board of Directors decrees dated 8 April 2025, Kep-00002/BEI/04-2025 and Kep-00003/BEI/04-2025 (Indonesia.go.id; Kompas.com), retrieved 13 August 2026. Both apply to shares on the Main Board, Development Board and New Economy Board, plus ETFs and DIRE (real estate investment funds).
This is the part that trips people up. Hitting ARB does not mean your stock is frozen with zero trading. It means no one can sell below that floor price. If buyers are still willing to buy at the floor, trades can keep happening right at that price, just not below it. The same logic runs in reverse at ARA: buyers cannot chase the price higher than the ceiling, but trading can continue at the ceiling.
What usually happens in practice is different: once a heavily sold stock hits ARB, sell orders pile up at the floor with few buyers willing to match them, so very little actually trades even though the mechanism itself has not banned trading outright. That pile-up, not the rule itself, is what makes a stock at ARB feel frozen.
Auto reject applies to individual stocks. A separate, market-wide mechanism kicks in when the IHSG (Indeks Harga Saham Gabungan, the IDX's main composite index tracking the whole exchange) itself falls sharply in a single day. This is the exchange's actual circuit breaker, and since the same 8 April 2025 rule change, it works in three steps:
Source: Bareksa, "Aturan Baru BEI Soal Trading Halt Berlaku Mulai 8 April 2025," retrieved 13 August 2026; Indonesia.go.id. This replaced an older 5% single-level halt threshold used through 2020 to 2025.
This is not a hypothetical rule. It has actually triggered twice on consecutive days: the IDX halted trading when the IHSG fell 8% on 28 January 2026, and again the next day, 29 January 2026, at 09:26 Jakarta time (CNBC Indonesia; Databoks). On both days, the whole exchange stopped for half an hour, every stock, not just the ones that individually hit their own ARB.
There is a third layer that is easy to confuse with auto reject but works differently. Unusual Market Activity (UMA) is a public notice the IDX issues when a stock's price or trading volume looks abnormal, whether it is repeatedly hitting ARA, repeatedly hitting ARB, or simply moving in a way that does not match any public information about the company. A UMA notice is a warning, not a trading halt by itself.
If BEI decides the situation needs more than a warning, it can go further and suspend the stock entirely, stopping all trading in that one name specifically, which can last anywhere from part of a day to much longer, unlike the fixed 30-minute market-wide halt described above (mstock by Mirae Asset Sekuritas, "Ini Aturan UMA dan Suspensi Saham dari BEI", retrieved 13 August 2026). Touching ARA or ARB repeatedly is one of the signals BEI watches for when deciding whether to issue a UMA notice, but hitting the price band on its own does not automatically trigger a UMA or a suspension.
So there are three separate mechanisms, each doing a different job:
| Mechanism | What triggers it | What it affects |
|---|---|---|
| Auto reject (ARA/ARB) | One stock's price moving past its daily band | That one stock's price band for the rest of the day |
| Trading halt | IHSG falling 8%, 15% or 20% in a day | The entire exchange, all stocks, for a fixed period |
| UMA / suspension | BEI's own judgment on unusual activity in one stock | That one stock specifically, duration varies |
None of these mechanisms tell you whether a stock is a good or bad holding, and none of them guarantee what happens the next trading day. A stock at ARB today can open at ARB again tomorrow if selling pressure has not eased, and a market-wide halt only pauses trading, it does not reverse the price move that triggered it.
What these rules are actually designed to do is slow down panic. A 30-minute pause gives investors, and the exchange itself, time to absorb new information instead of reacting instantly to a price already in free fall. That is the whole function. It is a speed bump, not a safety net.
Before assuming a stock is "frozen" or the market is "crashing," check the Market page in NetWort to see current sentiment, movers and whether the broader index itself is under real pressure, rather than reacting to one frozen price on a single screen.