Every scenario starts from something that happened on the Indonesia Stock Exchange, then asks a narrower question: what would a market of behavioural agents have done with that same shock?
MSCI warns on IDX free-float transparency; passive funds de-risk ahead of a possible exclusion wave.
Oct 2025: MSCI's new free-float methodology (lower of issuer vs KSEI data) hit the IHSG from its 8,355 high; Jan 27, 2026 MSCI freeze drove an 8% intraday drop wi...MSCI adds BREN + BRMS to Global Standard; ETFs must buy at the rebalance date.
Nov 2025 review: BREN, BRMS added to MSCI Global Standard (effective Nov 25, 2025); ICBP, KLBF removed. Inclusion events averaged ~$247M inflows per name; BREN +2...Large-cap Indonesian names get deleted from MSCI Standard; forced ETF selling.
The May 2026 MSCI review removed six Indonesian companies including Amman Mineral and Barito Renewables; passive funds with no discretion sold, IHSG -3.5% over th...Bank Indonesia cuts BI-Rate 25bps; cheaper funding lifts bank margins and the index.
Aug 19, 2025: BI-Rate cut to 5.00%. Event studies on 41 banks found no significant abnormal return — the cut was fully anticipated. 2025 saw 4 cuts in total; rate...BI hikes to defend the rupiah; costlier funding dents bank NIMs and growth stocks.
2024: BI held/hiked amid rupiah weakness toward 16,700/USD; a higher BI-Rate is a negative signal for bank returns in the panel data (negative and significant eff...The finance minister is replaced; markets test fiscal credibility overnight.
Sep 8-9, 2025: Prabowo replaced Sri Mulyani with Purbaya; IHSG fell ~1.6% on the reshuffle day after hitting an intraday record 8,022; rupiah forecast to slide to...Government pushes budget cuts; contractors and commodity-heavy names take the hit first.
2025 'budget efficiency' program: markets wavered over whether it was austerity or reallocation; state revenue shortfalls (partly Coretax rollout) plus the ambigu...President mandates energy exports run through state-owned firms; energy names gap down.
May 21, 2025: IHSG -3.54% to 6,094 after Prabowo's SOE export policy at the DPR; energy sector led the drop (-6%), compounded by a 10% participating-interest hand...A live presidential slip on fiscal policy spooks retail; brief dip, fast mean reversion.
Pattern modeled on recurring 2024-25 political headlines: a live statement misread by the market triggers a 1-2% intraday dip that mostly reverses within the week...New tax system rollout slips state revenue; mid-year fiscal shock to the index.
Mid-March 2025: IHSG sold off after Jan-Feb state revenue came in below target, driven by the rushed Coretax reporting system ahead of the administration's quick-...Rupiah breaks 17,000/USD; export-heavy names rally on the cheaper peso, importers and rate-linked names fall.
2024-25: rupiah slid toward 16,700-16,800/USD on MSCI + tariff stress. Cheaper currency is a tailwind for exporters (medcos, coal, palm) and a headwind for import...US tariff escalation hits export exposure; emerging-market risk-off, gold safe haven.
Apr 2, 2025 'liberation day': IHSG fell 8% through the 90-day pause window while regional peers did worse; investors rotated to gold as a safe haven; IHSG ended H...Brent jumps; coal and gas names bid, fuel-importing economy takes the hit.
Commodity cycle: ADRO/PTBA earnings track coal prices; an oil spike squeezes importers and consumer names, and is a headwind for the rupiah.Global risk-off sends gold to new highs; miners reprice sharply upward.
2024-25: gold bull run (above $2,600/oz) lifted gold-related emitters as a safe-haven rotation during tariff and MSCI stress.Foreign flows rotate back into the big four banks; the index's main driver.
2024: BBRI EPS growth 78% YoY; banks dominate IDX liquidity. BBRI/BCA/BBNI/BMRI/BRI drive a large share of IDX volume.Rate cuts + cheap financing revive property developers.
2025: property was the poster child of 'rate-sensitive but lagging' — 4 BI cuts through 2025, yet liquidity (M2) stayed thin and the 4 big prop names (BSDE, CTRA,...IDX30 names beat; momentum chasers move into leaders.
Quarterly pattern: positive earnings surprise season historically lifts momentum strategies and bank-heavy blue chips.Several names cut guidance; value investors probe the discount.
Quarterly pattern: guidance cut season rotates money into unaffected sectors and triggers value-style buying of temporarily-depressed blue chips.IDX hits the 5% circuit breaker and halts; LQ45 names overreact, then recover.
Mar 18, 2025: IHSG -5.02% triggered a trading halt; the MSCI freeze of Jan 27, 2026 did the same on an 8% intraday drop. Event studies on LQ45 show the overreacti...Speculative retail pile into small-cap 'gorengan' names; sharp unwind.
Recurring pattern Purbaya cited in 2025: 'gorengan' stocks (low float, concentrated) build parabolic retail-driven rallies that unwind violently when MSCI or OJK...Political cycle optimism; infrastructure and banks lead the bid.
2024 election pattern: new administration + 8% growth target bids infrastructure (JSMR, TLKM) and banks; LQ45 event studies around the 2024 election show positive...Mass demonstrations over policy; short political-uncertainty dip.
Aug 29, 2025: DPR demonstrations on allowances; IHSG -2.27% the session. Political-uncertainty dips in EMs typically run 5-10% when they touch policy credibility,...Pure drift: the deterministic market with no scenario shocks. The reference line every scenario is diffed against.
Each scenario page lists the real anchor, the shock schedule the run injects, and a link to the run's full event log. The log is one JSON object per line, and the desk replays from that same file, so what you watch and what happened are the same bytes.