SPCX Nasdaq-100 September 2026 quarterly rebalance — float-driven weight pulse (pre-announcement)

Generated by Grok Bot research on 2026-09-09. WebSearch + fetch ladder + native X. Treat as raw material — review before promoting.

Summary

Nasdaq’s published Nasdaq-100 methodology confirms a March/June/September quarterly rebalance: announce after the close on the sixth trading day prior to the effective date, effective at the open on the first trading day after the third Friday of the month, with low-float names weighted on Modified Market Cap = lesser of listed TSO or 3× free-float shares. Mapping that rule to September 2026 yields announce Fri Sep 11 after close and effective Mon Sep 21 before open — matching Gage’s street dates, but no Nasdaq IR/GIW September 2026 results release has been published yet (as of 2026-09-09). Secondary desks (JPMorgan / Min Moon via Briefs and crypto-wire reprints) cite a float-driven weight move ~1.25% → ~1.51% and ~$12.4B net passive buy; those figures are attributed estimates only, not Nasdaq-verified, and other secondary copy disagrees on the dollar size. Tie to vault spacex-lockup-calendar, spacex, and spacex-ipo-index-inclusion-mechanic as the demand pulse after already-vaulted Sep 9–10 unlock eligibility — do not re-file that calendar here. Later unlocks (~late Oct day-count steps; ~1.3B earnings-tied after Q3 mid-Nov) are supply context only.

Findings

Official calendar and methodology (Nasdaq primary)

• Quarterly rebalance schedule (methodology PDF): Rebalance Reference Dates = last trading day of Feb/May/Aug/Nov; Announcement = after the close on the sixth trading day prior to the Rebalance Effective Date; Effective = at market open on the first trading day following the third Friday in Mar/Jun/Sep/Dec. Source: Nasdaq-100 Index Methodology (NDX).
• September 2026 mapping (rule → calendar, not yet Nasdaq-confirmed results): Third Friday = 2026-09-18; first trading day after = Mon 2026-09-21 effective open. Counting six trading days prior to Sep 21 (no intervening holiday assumed) lands on Fri 2026-09-11. Reference date under the rule = last trading day of August 2026 (Aug 31). These street dates stay provisional until Nasdaq’s September results release.
• June 2026 precedent (IR primary): Nasdaq announced the June quarterly rebalance on 2026-06-11, effective prior to open Mon 2026-06-22 — consistent with the sixth-trading-day-prior rule once Juneteenth (Fri Jun 19) market closure is treated as a non-trading day. Source: Nasdaq-100 Index June 2026 Quarterly Changes. No analogous September 2026 IR release was found as of this pass.
• Weighting is not full-shares for low float: For weight calculations, Nasdaq uses Modified Market Capitalization: listed share classes only; each low-float security’s TSO is capped at three times free-floating shares; weight uses the lesser of reported TSO or 3× free-float shares × price. Ranking for selection/removal still uses Full Market Capitalization (listed + unlisted for direct listings). Source: Methodology_NDX.pdf.
• FAQ elaboration (Nasdaq Global Indexes): Cap applies while float ≤ 33⅓%; above that, full listed market cap is used for weighting. Float updates are reviewed at quarterly reviews only (not intra-quarter). Nasdaq does not anticipate future lock-up expirations in float until they have occurred and are supported by available share data. Weight interpolation is used so rising float repositions the name between next-largest/next-smallest by modified market cap. Source: Nasdaq-100 Methodology Changes FAQ (July 2026).
• Implication for SPCX: A lockup-driven float increase between the prior quarterly review and the Aug 31 reference date is the mechanical reason a weight increase can appear at the September rebalance — without implying Nasdaq has published SPCX’s post-rebalance weight yet.

Weight / passive-flow estimates (attributed secondary — not verified)

• JPMorgan / Min Moon (via Briefs Finance, 2026-09-08): Current NDX weight cited at 1.25% (19th by weight vs ~6th by market value >$2T); revised post-rebalance projection 1.51%; if so, ~$12.4B net buying from NDX-tracking funds/ETFs. Same piece attributes ~$1.7T NDX-tracking AUM at end-Q2 (incl. QQQ) to Nasdaq statistics (not independently re-fetched from Nasdaq here). Announcement expected “Friday after the close”; effective “Sept. 21.” Source: Briefs — Nasdaq 100 Rebalance May Boost SpaceX Weight.
• Same JPM figures reprinted (crypto-wire secondary): HTX / Marsbit reprint (2026-09-09) repeats 1.25% → ~1.51% and ~$12.4B net passive buy, float “nearly 30%” after >1B unlocks, announce Friday after close / effective Sep 21. Internal inconsistency in that reprint: abstract/body lead with $12.4B, while a later paragraph asserts “about $15.5 billion in passive buying is relatively certain” without a separate desk attribution — treat as unreconciled secondary noise, not a second verified estimate. Source: HTX Insights reprint.
• Bloomberg primary desk note: URL exists (Bloomberg — SpaceX weighting set to rise, dated 2026-09-08) but fetch failed (bot/challenge page). Do not invent Bloomberg’s dollar or weight figures from search snippets.
• Prior inclusion weight (context, not Sep estimate): Morningstar (post-IPO methodology explainer) reports SPCX received a ~1.3% NDX weight on July 7 Fast Entry add (then ~20th in QQQ). Useful as a pre-unlock baseline band; not a confirmation of today’s 1.25% or of the 1.51% desk call. Source: Morningstar — How Index Funds Are Adapting to Mega-IPOs.
• AUM figure tension (flag, do not flatten): June 2026 IR boilerplate says NDX is tracked by >200 products with >$800B AUM; Briefs/HTX cite ~$1.7T end-Q2. Different cutoffs/dates/scopes possible; neither validates a $12.4B flow without desk AUM × Δweight math disclosed. Sources: June IR; Briefs.
• Grain: Do not promote 1.25% / 1.51% / $12.4B (or $15.5B) as fact. They are desk/secondary attributions pending Nasdaq pro-forma weights and independent AUM × Δw verification. No buy/sell/size judgment in this clip.

Relationship to vault lockup / entity / index pages (no Sep 9–10 re-file)

• Vault priors (gh-read, not re-researched as news):
  • spacex-lockup-calendar — 424B4-dated three-pool calendar from prospectus date 2026-06-12; Sep 9 (90th day, up to 319.0M ex-affiliates) and Sep 10 (91st day affiliates, up to 59.1M) already vaulted. Do not duplicate that table here.
  • spacex — SPCX entity; NDX Fast Entry / July 7 add and lockup pointers live there; index-add status still open on the question page.
  • spacex-ipo-index-inclusion-mechanic — open question on passive cadence; already records July 7 NDX add as dated recap and prior Day-15 forced-buy estimate ranges ($4.3B Fool vs ~$7–12B pre-IPO consensus). This clip is the post-inclusion quarterly float-reweight pulse, not another Fast Entry event.
• Demand vs already-vaulted eligibility: Street narrative links the Sep N100 weight uptick to float rising after >1B shares already unlocked (Aug earnings-tied 20% + Aug 20 70-day + approaching Sep 9–10 steps). Eligibility ≠ observed selling (vault already flags that). The Sep 21 rebalance is a separate mechanical demand window timed to Nasdaq’s float snapshot as of the Aug reference date — not a re-statement of Sep 9–10 unlock share counts.

Later unlocks as supply context only

• Per vault spacex-lockup-calendar (424B4), further 180-day-pool day-count steps land Sep 24 / Oct 9 / Oct 24 (105/120/135th day, up to 328.4M each) — street “>1B by late October” aggregates those with prior eligibility, not a new primary count invented here.
• Q3 earnings-tied 28% / up to 1.3B remains calendar-day unknown until the First Earnings Release Date for Q3; street “mid-November” is secondary timing color (Briefs/HTX), not a Nasdaq or 424B4 fixed date.
• Use only as supply overhang context against the Sep 21 demand pulse — Gage owns any netting judgment. Sources for street color: Briefs; HTX reprint. Primary share caps remain on vault lockup page / 424B4.

Contradictions and open questions

• Street dates vs Nasdaq results: Methodology + June precedent support Sep 11 announce / Sep 21 effective, but September 2026 results release not yet on ir.nasdaq.com as of 2026-09-09 — dates remain provisional.
• $12.4B vs $15.5B (and wider chatter): JPM/Min Moon via Briefs = ~1.51% / ~$12.4B; HTX reprint also floats ~$15.5B as “relatively certain” without desk math; Grok X news clusters (not cited as grain) mentioned other dollar bands. No primary verification.
• Current weight 1.25% vs Morningstar July 1.3%: Drift from price/relative moves and prior float updates is plausible; Nasdaq GIW live weight file not fetched this pass.
• Tracked AUM $800B (June IR) vs $1.7T (desk-attributed Nasdaq Q2 stat): Scope/date mismatch unresolved; any $ flow estimate inherits that uncertainty.
• Float “nearly 30%”: Secondary claim; vault IPO float was ~4.9% with greenshoe — later float needs issuer/ownership primary, not assumed from desk copy. Nasdaq FAQ: future unlocks not in float until effective and documented.
• Bloomberg article body unread (bot challenge) — may contain earlier/alternate desk projections; gap remains.
• Open for Gage: wait for Nasdaq pro-forma / GIW weights post-Sep 11 close before treating Δweight or $ flow as operational fact.

Provenance

Method: Grok Bot / WebSearch / fetch ladder / native X
Generated: 2026-09-09
Rounds: 2 of 3 (early-exit — calendar/methodology primaries confirmed; weight/$ remain attributed secondary; Sep IR not yet published)
URLs fetched: 8 successful body retrieves, 3 failed/blocked, vault gh reads separate
Fetch notes: Methodology PDF + FAQ PDF via WebFetch OK; June IR via curl after WebFetch timeout; Briefs + HTX + Morningstar OK; Bloomberg bot-challenged (curl); nasdaq.com newsroom methodology explainer timed out; rsfundmanagement calendar 500.

Web sources:

• Nasdaq-100 Index Methodology (NDX PDF) — official rebalance calendar; Modified Market Cap / 3× float cap.
• Nasdaq-100 Methodology Changes FAQ (July 2026) — 33⅓% threshold; quarterly-only float updates; no anticipation of future lockups; Sep 2026 interpolation example.
• Nasdaq IR — June 2026 Quarterly Changes — announce Jun 11 / effective Jun 22 precedent; >$800B tracked AUM boilerplate.
• Briefs Finance — N100 rebalance / SPCX weight — attributed JPM Min Moon 1.25%→1.51% / ~$12.4B; street Sep 11/21 dates; later-unlock color.
• HTX Insights reprint — same JPM figures; also unreconciled ~$15.5B line.
• Morningstar — mega-IPO index adaptations — July 7 Fast Entry ~1.3% initial NDX weight context.
• Bloomberg article URL (body not retrieved) — failed bot challenge; cited as miss only.

Vault priors (gh api, pmcclelland/brain main):

• vault/projects/stock-market/wiki/concepts/spacex-lockup-calendar.md
• vault/projects/stock-market/wiki/entities/spacex.md
• vault/projects/stock-market/wiki/questions/spacex-ipo-index-inclusion-mechanic.md

X sources:

• none found — searched search_news (SPCX / Nasdaq-100 rebalance) and recent posts from @Nasdaq, @marketbriefs, @SteveSosnick; no high-signal permalinks on the Sep weight/flow claim. Grok news clusters returned dollar chatter but are not cited as grain per skill rules. Sosnick quotes in Briefs are secondary HTML only.

Grokipedia:

• not used