Currently baked-in (static)
Everything you see right now is a static snapshot from May 2026. Pros: zero API costs, instant load, fully cacheable. Cons: numbers stale as soon as a holding changes or a new deal hits the pipeline.
Top 10 by weight pulled from StockAnalysis.com / issuer fact sheets
May 2026 snapshot
Free
QQQ NVDA 8.75%, AAPL 7.34%, etc. — hand-coded.
Issuer reports / Yahoo Finance
May 2026 snapshot
Free
$327B QQQ, $480B VTI, etc.
Renaissance Capital, Dealroom, press tenders
May 2026 reports
Free
User-editable via valuation slider for sensitivity analysis.
S&P, Nasdaq, FTSE Russell, MSCI rulebooks
Annually updated rules
Free
Codified as logic, not data — only changes when rules change.
FTSE Russell announcement Mar 2026
2026 schedule confirmed
Free
Dates locked: Apr 30 rank → May 22 prelim → Jun 26 effective.
Could be wired live (easy)
High-ROI upgrades that take a few hours each. iShares and SSGA both publish daily CSVs at stable public URLs. A Next.js route handler with 24h revalidate handles this elegantly.
iShares ETF holdings (IWB, IWM, IVV, IWF, IWD)★ rec
ishares.com daily CSV exports
Could be daily-refreshed
Free
~2 hours to wire. Stable URL pattern: /us/products/{id}/{etf}/1467271812596.ajax?fileType=csv
SPDR ETF holdings (SPY, XLK, XLF etc.)★ rec
ssga.com daily holdings exports
Could be daily-refreshed
Free
~2 hours to wire. SSGA serves XLSX format.
Renaissance IPO ETF holdings★ rec
renaissancecapital.com or Finnhub
Could be daily-refreshed
Free (Finnhub free tier sufficient)
Critical — this is THE most-impacted ETF on new IPOs.
Could be wired live (paid)
Requires a data feed. Worth it if traffic justifies it — say, $20-50/mo at scale.
Vanguard ETF holdings (VTI, VGT, VOO)
Finnhub, FMP, Polygon
Daily refresh
$10-50/mo depending on call volume
Vanguard doesn't publish clean public CSVs.
Finnhub or scraper
Daily refresh
$10-30/mo
Invesco site is JS-rendered; clean API needed.
Pre-IPO valuations (secondary market)
Forge Global, EquityZen API
Updated as trades clear
$200+/mo for API access
Probably overkill for v1 — press reports are good enough.
Renaissance Capital data feed
Real-time on S-1 filings
Enterprise pricing
Hard to justify cost. Manual updates work fine.
Should NOT be auto-pulled
Either the data isn't worth the integration cost, or republishing creates legal/licensing risk.
Russell preliminary additions/deletions
FTSE Russell PDFs
Updated weekly May 22 – Jun 18
Free PDF, but terms of use
Link out to FTSE Russell rather than republish. We point users to lseg.com.
Polygon, Alpaca, IEX Cloud
Real-time
$50-200/mo
Not needed for inclusion-impact math. Skip until you need a watchlist feature.
The honest answer
Today, nothing pulls automatically. Static is fine for v1.
Wiring up the iShares and SSGA CSVs is the highest-ROI next step and takes about half a day. That covers IWB, IWM, IVV, IWF, IWD, SPY, and the entire SPDR sector lineup (XLK, XLF, XLE, etc.). Once done, the dilution math becomes always-current and the eligibility matrix recomputes nightly.
Everything else can be added as ETFIPO grows — start free, layer in paid feeds when traffic justifies them.