Jakarta. Indonesia’s benchmark stock index suffered one of its most volatile weeks in recent years in late January, prompting the resignation of senior leaders at both the country’s financial regulator and stock exchange as authorities grappled with a sharp market sell-off linked to global index policy changes.

The Jakarta Composite Index (JCI) slid heavily during the Jan. 26–30 period, falling 6.94% week-on-week to close at 8,329.61, down from 8,951.01 the previous week, according to data from the Indonesia Stock Exchange (IDX). Market capitalization dropped 7.37% to Rp15,046 trillion ($894 billion), from Rp 16,244 trillion a week earlier.

The most dramatic moves came midweek. On Wednesday, Jan. 28, the JCI plunged as much as 8% intraday, forcing the IDX to halt trading temporarily to stabilize the market. A day later, the exchange imposed two separate trading halts after the index again fell sharply.

The selloff followed an announcement by MSCI Inc., the global index provider, which introduced interim measures related to its assessment of the free float of Indonesian-listed companies. The policy move rattled investor confidence, triggering heavy selling pressure across the market.

Foreign investors were net sellers during the period, posting net outflows of Rp 1.53 trillion on the final trading day of the week. Year-to-date in 2026, cumulative foreign net selling has reached Rp 9.88 trillion rupiah, the exchange said.

IDX Corporate Secretary Kautsar Primadi Nurahmad said average daily trading value jumped 29.28% to Rp 43.76 trillion during the week, from Rp 33.85 trillion previously. 

The market turmoil quickly spilled into the leadership ranks of Indonesia’s financial institutions. On Friday morning, Jan. 30, IDX President Director Iman Rachman announced his resignation, citing responsibility for recent conditions in the capital market.

Later that evening, Financial Services Authority (OJK) Chairman Mahendra Siregar also stepped down, alongside two senior officials overseeing capital markets: Inarno Djajadi, Chief Executive for Capital Market, Derivatives Finance and Carbon Exchange Supervision, and I.B. Aditya Jayaantara, Deputy Commissioner for Issuers, Securities Transactions, Special Examinations, Derivatives Finance and Carbon Exchange Supervision.

Following the announcement, OJK Vice Chairman Mirza Adityaswara also tendered his resignation, marking an unprecedented leadership shake-up at Indonesia’s key financial watchdog.

Even as markets reeled, Indonesia’s retail investor base continued to expand. By the end of January 2026, the total number of Single Investor Identification (SID) accounts reached 21.04 million, up by 673,218 from the end of 2025. Throughout 2025, the number of capital market investors grew by more than 5.49 million, underscoring rising public participation in financial markets.

Stock investors alone now number close to 9 million. As of the end of January, equity investor accounts stood at 8.98 million, an increase of 367,958 from the end of last year.

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Editor’s note: The headline has been corrected to more accurately reflect the story. We regret the error.