Two large-cap stocks that recently went public through their Initial Public Offerings (IPOs) have once again attracted market attention. These stocks—PT Chandra Daya Investasi Tbk (CDIA) and PT Indokripto Koin Semesta Tbk (COIN)—were previously flagged under Unusual Market Activity (UMA) and eventually suspended from trading by the Indonesia Stock Exchange (IDX).

After registering six consecutive days of hitting the Upper Auto Rejection (ARA) limit, both CDIA and COIN were labeled as UMA on Wednesday (July 16, 2025). By the following day, Thursday (July 17, 2025), IDX officially suspended trading in these two stocks.

The suspensions were not without cause. After being placed under UMA status, both issuers were swiftly suspended by the exchange.

UMA, or Unusual Market Activity, is a warning issued by the IDX when a stock exhibits abnormal price movements or trading volumes. This does not automatically indicate that the stock is involved in violations or illegal actions, but rather serves as a precautionary measure to protect investors from potential price manipulation or irregular transactions.

Why can a stock be labeled as UMA? It often results from a rapid and substantial increase or decrease in price within a short period, a sudden spike in trading volume, or a significant rise in transaction frequency.

Such a scenario occurred with CDIA, where the stock price surged dramatically in a short time. In fact, buy orders in the negotiated market reached as high as Rp 1,400, even though the regular market price had not yet hit that level.

Following its six-day streak of sharp gains through ARA, CDIA was flagged with UMA. Unfortunately, the next day, the stock was immediately suspended without being given a trading opportunity to stabilize.

A similar case unfolded with COIN. After also experiencing six consecutive days of sharp gains and ARA, it was placed under UMA and then suspended the very next day.

Typically, UMA protocol allows stocks to resume trading for one day after six days of consecutive ARA. If the stock continues hitting ARA during that session, suspension may be enforced the following day.

However, CDIA and COIN deviated from this pattern, as they were suspended immediately after receiving UMA status, without being granted that one-day trading window.

It is important to note that there is no fixed formula for UMA or suspension enforcement; decisions are subject to the discretion and policy of the IDX. In some cases, acceleration board stocks are permitted to hit ARA for up to ten consecutive days before facing suspension.

Lastly, being placed under UMA does not necessarily imply any wrongdoing or a guaranteed suspension. However, suspension may follow if clarifications are deemed inadequate, extreme price movements continue, or signs of market manipulation are detected.