Indonesia's JCI Falls 0.27% as BYAN Becomes Biggest Drag

A sharp decline in Bayan Resources shares put disproportionate pressure on Indonesia's benchmark equity index on Monday.

The Jakarta Composite Index, or JCI, ended the first trading session on September 21, 2026 at 6,423.51, down 17.65 points or 0.27%.

The index had traded as high as 6,451.33 before sliding to an intraday low of 6,388.25 and recovering part of its losses before the midday break.

BYAN Alone Cost the Index More Than Eight Points

PT Bayan Resources Tbk was the largest negative contributor.

BYAN fell roughly 3.6% to Rp13,325, subtracting about 8.2 index points from the JCI, according to Samuel Sekuritas' midday market update.

Its influence reflects the way a market-capitalization-weighted index works.

A decline in a large company can have a far larger impact on the benchmark than a similar percentage move in a smaller stock.

Large Banks Added to the Pressure

BYAN was not the only drag.

BBCA fell around 0.8%, subtracting approximately 4.4 points from the index.

TLKM lost about 1.6% and removed another 3.7 points.

BBRI and BMRI also declined, reducing the JCI by around 2.9 and 2.5 points respectively.

The concentration of losses among large-cap stocks explains why the benchmark remained negative even though hundreds of individual shares were still higher.

MORA, BUMI and TPIA Limited the Losses

Several stocks moved in the opposite direction.

MORA and BUMI each contributed roughly 1.5 positive index points.

TPIA added around 1.3 points, while ASII and BRPT each contributed roughly 1.2 points.

Those gains helped the benchmark recover from its session low, but they were not enough to offset the weight of the major laggards.

Foreign Investors Were Net Sellers

International investors recorded approximately Rp216.24 billion of net selling during the first session.

ANTM recorded the largest foreign net sell at about Rp100.62 billion.

BMRI followed with roughly Rp79.91 billion, TLKM with Rp53.47 billion and BBCA with Rp50.77 billion.

Foreign flows were not universally negative.

TPIA, TINS, BBRI, COIN and BULL still attracted net foreign purchases.

That points to stock rotation rather than indiscriminate selling across the entire Indonesian market.

Trading Value Reached Rp5.74 Trillion

First-session trading value reached roughly Rp5.74 trillion.

Around 14.28 billion shares changed hands in approximately 1.06 million transactions, according to one midday market data snapshot.

IDX Mobile data cited separately showed 339 stocks advancing, 311 declining and 313 unchanged.

Small discrepancies between market-data providers can reflect different cut-off times and instrument coverage.

Energy Was Not the Weakest Sector

One important correction to some early market summaries concerns the energy sector.

Energy was actually up roughly 0.13% by the end of the first session despite BYAN's decline.

Infrastructure was the weakest sector, falling about 0.40%.

Consumer non-cyclicals declined roughly 0.38%, while financials dropped about 0.19%.

Transportation and logistics led the gainers with a 1.47% rise.

This illustrates why a major stock can be a large index drag without necessarily pulling its entire sector lower.

Bank Indonesia Is the Next Domestic Catalyst

Investors are now looking toward Bank Indonesia's September policy meeting.

BI's official calendar schedules its monthly Board of Governors Meeting for September 22–23, 2026.

Markets will focus on the policy rate as well as the central bank's assessment of inflation, the rupiah, capital flows and domestic growth.

That decision comes at a time when global monetary conditions have tightened.

The Fed Just Raised Rates

The U.S. Federal Reserve increased its target federal funds range by 25 basis points to 3.75%–4.00% at its September meeting.

The decision was unanimous, with a 12-0 vote.

The Fed said economic activity remained solid but inflation was still elevated.

The move represented the first U.S. rate increase in about three years and reinforced expectations that global financing conditions may remain restrictive.

Japan Tightened Too

The Bank of Japan also raised its benchmark rate on September 18.

The policy rate increased to 1.25%, the highest level in 31 years.

The decision passed by a 7-2 vote.

Japan's move adds to the global shift toward tighter policy as major central banks respond to inflationary pressure.

China Held Its Benchmark Rates

China took a different path.

The one-year Loan Prime Rate remained at 3.00%, while the five-year rate stayed at 3.50% for a 16th consecutive month.

The decision was broadly expected.

China's policymakers face a balance between supporting domestic demand and avoiding additional pressure from large interest-rate differentials with the United States.

Treasury Yields Remain Near 5%

U.S. bond yields remain another important variable for emerging markets.

The 10-year Treasury yield was around 4.97% on September 21, after declining slightly as oil prices eased.

High Treasury yields can increase the relative appeal of U.S. fixed-income assets and affect global capital allocation.

For markets such as Indonesia, that can feed into equity flows and currency pressure.

Oil Is Still Trading Around $100

Energy prices remain elevated even after Monday's decline.

Brent crude fell about 1.7% to $102.09 per barrel, while WTI dropped to around $98.33.

The decline reflected hopes for diplomatic progress in the Iran conflict and signs that regional oil flows were proving more resilient than feared.

Still, attacks by Iran-backed Houthi forces on Saudi targets have kept geopolitical risks elevated.

Trump-Xi Meeting Is Also in Focus

Global investors are also watching the next U.S.-China summit.

China's Foreign Ministry confirmed that President Xi Jinping will visit the United States from September 23 to 25.

Xi and U.S. President Donald Trump are expected to meet on September 24.

Their discussions are expected to cover major elements of the bilateral relationship, including trade, technology, supply chains and artificial intelligence, as well as broader international issues.

The outcome could affect sentiment toward global trade and technology companies, though no specific breakthrough should be assumed before the talks occur.

Bessent and He Lifeng Prepared the Ground

U.S. Treasury Secretary Scott Bessent and Chinese Vice Premier He Lifeng held economic discussions ahead of the leaders' summit.

Those contacts were intended to maintain communication and prepare for high-level talks.

For markets, the key issue will be whether political dialogue eventually leads to concrete changes in tariffs, investment restrictions, technology controls or supply-chain policy.

U.S. Durable Goods Data Comes Friday

Investors will also receive another U.S. economic signal later this week.

The U.S. Census Bureau is scheduled to release August durable-goods orders on September 25.

The report measures orders for long-lasting manufactured products and can provide clues about business investment and industrial demand.

A major surprise could affect expectations for growth and future U.S. monetary policy.

Indonesia Underperformed a Stronger Asia Session

Interestingly, the decline in Indonesia did not reflect a broad Asian selloff.

Around midday, Japan's Nikkei was up roughly 1.4%, South Korea's Kospi 1.5%, Shanghai around 0.6%, and Hong Kong's Hang Seng about 0.6%.

That suggests Indonesia's first-session weakness reflected a combination of domestic positioning and stock-specific pressure rather than a uniform regional risk-off move.

Bottom Line

Indonesia's JCI fell 0.27% to 6,423.51 in the first session on September 21.

BYAN was the largest single drag, falling about 3.6% and subtracting more than eight index points.

BBCA, TLKM, BBRI and BMRI also weighed on the benchmark, while foreign investors posted roughly Rp216.24 billion of net selling.

The domestic market is now entering a catalyst-heavy week.

Bank Indonesia meets on September 22–23, while investors are also digesting rate hikes from the Federal Reserve and Bank of Japan, U.S. Treasury yields near 5%, oil around $100 per barrel and the upcoming Trump-Xi summit.

Because these figures are first-session data, they should be treated as a midday market snapshot rather than the final closing picture for September 21.

Disclaimer: This article is for informational and educational purposes only and does not constitute personalized investment advice or a recommendation to buy, sell or hold any security.