Institutional Ownership & 13F Flow Tracker

Methodology

Data. The universe is the S&P 500. For each company, Alpha Vantage's INSTITUTIONAL_HOLDINGS endpoint is pulled and only the top-level totals are kept: total institutional holders and shares, the counts and share totals of holders who increased, decreased or left their position unchanged, and total institutional ownership as a % of shares outstanding. The endpoint also returns a per-holder holdings list (thousands of rows for a mega-cap). This page doesn't use it.

Flow metrics. Two are shown because they answer different questions. Holder breadth is holders increased / (holders increased + holders decreased) × 100. It's a headcount: of the institutions that changed their position (unchanged holders are excluded), what share were adding? Above 50% means more added than trimmed. Net share flow is (shares increased − shares decreased) / total institutional shares × 100. It's a magnitude, scaled to the institutional share base, so a few large funds moving a lot of stock show up even if most holders didn't move. A stock can have positive breadth (most holders adding) and negative net flow (the sellers sold much more) at the same time. That divergence is informative, so both are shown.

Flow vs. momentum test. A single-snapshot cross-sectional regression: net share flow this run against each stock's trailing 3-month return relative to SPY, from Relative Strength Leaders/Laggards (Pearson and Spearman, as on Factor Analysis). It is not a forward-looking test across snapshots, because 13F positioning moves too slowly week to week for that. The same reasoning applies on Margin & Leverage Cycle and Equity Risk Premium by Sector. If Relative Strength Leaders/Laggards hasn't refreshed, this section shows a warning and the rest of the page still works.

Limitations. 13F filings are quarterly and can lag quarter-end by up to 45 days, so this is a slow, backward-looking picture, not a live feed. Coverage is US institutional long-only managers with at least $100M in AUM who must file a 13F. It doesn't capture short positions, options or derivatives exposure, retail flow, or non-US institutions. A rising ownership % can also come from buybacks shrinking the share count rather than net institutional buying, and one quarter of 13F reshuffling among a few large index funds can swing net share flow for a stock with a small institutional base. Leaderboards require at least 5 institutional holders on file to reduce that noise.

Sector medians are published only when at least 3 companies in the sector have a usable value. Refreshes weekly (Saturday morning, after Share Count Trends), because the page is built around a flow trend that accumulates week over week. Sector and company name come from Sector Beeswarm.