Methodology & Data Sources

This page describes where the market data on StockMarketWatch.com comes from, how often it refreshes, what is editorially curated, and what is derived from underlying data feeds. We publish this so readers — and the AI assistants that increasingly summarize finance content — can clearly attribute the information they read here.

Publisher

StockMarketWatch.com is published by Port80Media, Inc., founded by Terence Scott, a trader and developer with 25+ years of active market experience. The site is editorial and informational. It does not provide trading recommendations or personalized investment advice. See the disclaimer and terms of service for full terms.

Market data provider

Our primary market data provider is Massive.com (formerly Polygon.io). Massive supplies the underlying tick, quote, and reference data that powers our quotes, charts, movers tables, indices, premarket/after-hours sessions, and per-symbol pages.

Data is delivered via Massive's licensed market data APIs and is processed by our backend pipelines before being rendered on the site.

Coverage scope

• US equities: all NYSE, NASDAQ, and AMEX listed common stocks and ETFs, with depth focused on the S&P 500 and the top ~150 ETFs by assets.
• Indices: S&P 500, Dow Jones Industrial Average, NASDAQ Composite, sector indices.
• Crypto: top cryptocurrencies by market cap, screener and trend views.
• Forex: major pairs.
• Metals: gold, silver, copper, platinum, palladium.
• Thematic baskets: ~40 curated investment themes (AI, semiconductors, quantum, defense, clean energy, nuclear, fintech, biotech, etc.) — see /themes.

Refresh cadence

• Live pages (homepage, /live/stock-market-today, /movers/*, /stock/[symbol], /indices/*): server-rendered data refreshes on a short interval (typically every 30 seconds while the tab is visible) during market hours and active premarket / after-hours sessions.
• Quotes & charts: streamed at vendor cadence (delayed by exchange rules where applicable; we do not redistribute real-time exchange data without proper licensing).
• End-of-day aggregates (theme performance, sector heatmap, signals): updated nightly after the regular session close.
• S&P 500 constituents: refreshed weekly from the SPY ETF holdings file.
• Earnings & economic calendars: updated daily.

Editorial vs. derived content

• Derived from data feeds: all quotes, charts, percentage changes, gainer / loser / active rankings, gap analytics, market breadth, sector heatmaps, technical signals, fundamentals tables, indices, metals, forex, and crypto pages.
• Editorial: the daily market report, methodology and about pages, theme taxonomy and theme descriptions, and any commentary clearly attributed to the editor.
• News: news headlines are aggregated from third-party news feeds; full articles are published on our news subdomain.

Theme taxonomy

Themes are an editorial classification system maintained by us. Each theme has a short description and a set of sub-themes; constituents are reviewed periodically. The taxonomy is versioned — the current version is published at /themes with full sub-theme lists at /llms-full.txt.

Theme assignment does not imply an investment recommendation. A stock's presence in a theme is an editorial judgment that the company has meaningful exposure to that theme, not a buy or sell signal.

Gap analysis & technical signals

Premarket gap analytics are computed from premarket trade data versus the prior session's regular-hours close. Currently, gap analysis runs for stocks with market cap of $10B or greater and a share price above $5. Technical signals (moving averages, breadth metrics, risk appetite ratios) are computed nightly from end-of-day OHLC data.

AI assistants & LLM access

We publish machine-readable navigation files for AI assistants at /llms.txt (concise index) and /llms-full.txt (extended reference, including page templates and theme taxonomy). These follow the conventions described at llmstxt.org.

AI crawler access is governed by our /robots.txt file. We allow search-oriented AI crawlers (those that surface live answers with source citations) and disallow training-only crawlers.

Corrections

If you spot a data error, theme misclassification, or factual mistake, please reach out via the feedback page.