IDX Revises ARB Rule Again, Rp11-Rp14 Stocks Can Now Drop Rp1

PT Bursa Efek Indonesia, or the Indonesia Stock Exchange (IDX), has once again revised its Auto Rejection Bawah (ARB) rule, the daily lower price limit for stock trading. This time the target is stocks priced between Rp11 and Rp14 per share. The ARB, previously calculated as 7% of a stock's price, has been replaced with a flat Rp1.

The change took effect Tuesday, October 20, 2026. According to CNN Indonesia, the new rule applies through December 31, 2026. That makes it a temporary policy rather than a permanent change, one that could be reassessed as the year wraps up.

What actually changed

Before this revision, stocks priced Rp11 to Rp14 used a percentage-based ARB of 7%, the same formula applied to most other stocks on the exchange. Now that limit has been replaced with a fixed nominal cap: stocks in this price band can fall by a maximum of Rp1 in a single trading day.

For context, if a stock opens at Rp12, under the new rule the lowest price it can reach that day is Rp11. Once that level is hit, the IDX trading system automatically rejects sell orders below it.

What hasn't changed is the Auto Rejection Atas (ARA), the upper price limit. detikFinance reported the ARA for the Rp11-Rp14 range stays at 35%, unchanged from before. So this revision is purely about the downside.

Why IDX made the adjustment

In its official statement, quoted by CNBC Indonesia, the exchange said the adjustment is part of its effort to keep trading "orderly, fair, and efficient" and to support better price discovery. That is the only official explanation the exchange has released for the change.

The word "again" in IDX's own statement signals this isn't the first time the exchange has tweaked ARB mechanics for low-priced stocks. The exchange appears to routinely fine-tune this formula, specifically for the group of stocks priced below Rp50, commonly called penny stocks or "saham gocap" among retail investors in Indonesia.

ARB and ARA, two terms worth understanding

Auto Rejection Bawah is the limit on how far a stock's price can fall within a single trading session. Once a stock hits that floor, the system automatically rejects any sell order priced below it, meaning no trade can happen lower that day.

Auto Rejection Atas works the opposite way, capping how high a stock's price can climb in a session. Both mechanisms exist to prevent wild intraday price swings and to give the market time to absorb new information gradually.

For extremely low-priced stocks like those in the Rp11-Rp14 range, a small percentage limit becomes impractical. Seven percent of Rp11 comes out to roughly Rp0.77, but IDX stock prices move in whole rupiah increments. Switching to a fixed Rp1 cap makes the limit far easier for the trading system to enforce.

Who's directly affected

Stocks priced Rp11 to Rp14 form a narrow, very specific group. These are issuers whose share prices have eroded well below the exchange's average nominal level, either through a long decline or because they were listed at such a low price from the start.

For investors holding or watching stocks in this band, the Rp1 cap narrows the daily downside range compared to the old 7% formula. Meanwhile, because the ARA stays at 35%, the potential daily upside for these stocks is now considerably wider than the potential downside while the new rule is in force.

What it means for investors

There are a few concrete things worth tracking. First, check whether the stock being held actually falls within the Rp11-Rp14 range, since only this specific group is covered by the new rule, not every penny stock on the exchange.

Second, note that since October 20, 2026, the daily downside limit for stocks in this range is a flat Rp1 rather than a percentage. That means the higher a stock sits within the Rp11-Rp14 band, the smaller its maximum percentage drop compared to the old 7% formula.

Third, remember the ARA remains at 35%, so the gap between the upper and lower limits has widened. Price patterns for stocks in this group could look unusual compared to normal trading, particularly when negative sentiment would typically trigger a sharp drop.

Fourth, since the rule runs only through December 31, 2026, investors with longer-term positions in this group should watch for official IDX announcements near year-end. There's no guarantee the flat Rp1 limit will continue afterward, or that the exchange won't revert to the old percentage-based format.

IDX keeps tweaking rules for low-priced stocks

Adjusting the ARB for extremely low-priced stocks is not a new move for the exchange. The word "again" used in IDX's own statement suggests the penny stock segment draws particular regulatory attention, likely because these stocks are prone to speculation and extreme price swings in short periods.

By narrowing the ARB formula into a fixed nominal figure for a specific price band, the exchange appears to be aiming for a mechanism that's more precise and easier for its electronic trading system to enforce, rather than continuing to rely on percentages that translate into tiny, hard-to-execute rupiah fractions.

What to watch through year-end

A few things are worth following after this announcement. First, how liquidity in Rp11-Rp14 stocks responds once the new rule has been running for several trading days. Second, whether IDX rolls out similar adjustments for other sub-Rp50 price bands, given the gradual pattern of revisions suggested by the exchange's own language. Third, any follow-up announcement near December 31, 2026 on whether this rule gets extended, revised again, or reverted to the original percentage-based format.

What is Auto Rejection Bawah (ARB)?

ARB is the daily lower price limit on the Indonesia Stock Exchange. Once a stock's price falls past this threshold, the system automatically rejects sell orders below that level.

Which stocks are affected by this change?

The new rule applies specifically to stocks priced between Rp11 and Rp14 per share, a band commonly known in Indonesia as penny or "gocap" stocks.

How long will this ARB rule apply?

CNN Indonesia reports the rule takes effect from October 20, 2026 through December 31, 2026.

Did the upper limit (ARA) for this price band change too?

No. detikFinance reported the ARA for stocks in the Rp11-Rp14 range stays at 35 percent; only the ARB was adjusted.