How to Track Institutional Portfolios with AI

Institutional portfolios can be tracked through Form 13F, the quarterly holdings report that every institutional investment manager with $100 million or more in section 13(f) securities, mainly US stocks and securities, files with the SEC. An AI assistant connected to 13F data can track exits and changes in share count, list new positions, compare quarters or institutions. This article shows how to do this, including example prompts using the portfolio of Berkshire Hathaway, Tiger Global, Bridgewater, Coatue and Appaloosa.

What does Form 13F contain about an institutional portfolio?

Who files and when

Coverage and limits

A 13F lists long positions in 13(f) securities on the last day of the quarter. Short positions, mutual fund shares, cash, most bonds, private holdings and written options are excluded from the report. A manager can request confidential treatment for a position for up to one year. The position then appears in a later amendment. Berkshire Hathaway published its holdings for the quarter ended 30 June 2026 on 14 August 2026, the filing deadline. A filing made on the deadline shows a portfolio that is 45 days old when it is published and about four and a half months old when the next filing is due.

Which other SEC filings show institutional positions?

Form 13F is one of several filings that show what investors hold. Form ADV and Form N-PORT come from investment advisers and registered funds, and they answer different questions: Form ADV describes the adviser firm, and Form N-PORT lists the holdings of each mutual fund, ETF or closed end fund.

For a hedge fund or a family office, Form 13F gives the equity positions, Schedule 13D and 13G give stakes above 5 percent with a shorter delay, and Form ADV gives the size of the firm and its private funds. For a mutual fund or an ETF, Form N-PORT gives the full portfolio, including the bond and derivative positions that a 13F excludes.

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          For Tiger Global Management, show the regulatory assets under management and
        

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          the private funds with their gross asset value from its latest Form ADV, then
        

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          compare the total with the value reported on its latest 13F.
        

How to track an institutional portfolio with AI?

The prompts below run in Claude with the SEC-API.io connector or in ChatGPT with the SEC-API.io plugin. The assistant queries the Form 13F holdings and cover page data, sums the rows for each security and calculates the changes. The figures in the output tables come from the 13F filings named under each table.

Connect the data

In Claude, add the SEC-API.io connector under Settings, Connectors, Add custom connector, with the URL https://api.sec-api.io/mcp?apiKey=YOUR_API_KEY. In ChatGPT, add the same URL as the SEC-API.io plugin in Developer mode. A free API key is available at sec-api.io/signup. The full setup is described in How to access SEC financial data in Claude and How to access SEC financial data in ChatGPT.

Exits and reductions

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          Which positions did Berkshire Hathaway exit or cut by more than 30 percent
        

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          between its 13F for 31 December 2025 and its 13F for 31 March 2026? Show the
        

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          share count and the value at 31 December 2025 for each, sorted by value.
        

What comes back:

• The number of rows in the filing fell from 110 to 90. The other exits were HEICO, Liberty Formula One, Charter Communications, Lamar Advertising, Allegion, Diageo, Atlanta Braves Holdings and Liberty Latin America.
• The seven exits in the table had a combined value of $10.74 billion at 31 December 2025.
• In the same quarter, the New York Times position rose from 5,065,744 to 15,146,535 shares.

Position history

          1
          Track Berkshire Hathaway's Alphabet position across its last four 13F filings.
        

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          For each quarter, show the filing date, Class A shares, Class C shares, total
        

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          shares, reported value and the position's share of the total 13F value.
        

What comes back:

• The share count was 17,846,142 for two quarters. It then rose 3.2 times in the first quarter of 2026 and 1.8 times in the second.
• Class C shares first appear in the 31 March 2026 filing. A query on the ticker GOOGL alone returns 78,791,167 shares for 30 June 2026 and omits 27,188,433 shares.
• The value rose from $4.34 billion to $37.76 billion.

Quarter over quarter changes

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          Compare Berkshire Hathaway's two most recent 13F filings. Add up all rows for
        

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          each security, treat Alphabet Class A and Class C as one position, and show
        

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          shares in both quarters, the change in shares and in percent, and the value at
        

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          the latest quarter end. List new positions, exits, increases and reductions
        

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          separately, and list the eight largest holdings by value with their share of the
        

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          total portfolio.
        

What comes back:

Berkshire Hathaway Inc, Form 13F-HR for 30 June 2026 (filed 14 August 2026, accession number 0001193125-26-352200) against 31 March 2026 (filed 15 May 2026, accession number 0001193125-26-226661). Total reported value: $299.25 billion across 89 rows, against $263.10 billion across 90 rows.

• Alphabet moved from the 7th largest position, at 6.3 percent of reported value, to the 3rd largest, at 12.6 percent. Berkshire added 24,541,369 Class A shares and 23,603,218 Class C shares.
• Apple, American Express, Coca-Cola, Chevron, Occidental Petroleum, Chubb, Kraft Heinz and Moody's have the same share count in both quarters. Their value changes result from price moves.
• Berkshire continued to reduce Bank of America: 568,070,012 shares at 30 September 2025, 517,295,934 at 31 December 2025, 513,624,165 at 31 March 2026 and 483,394,015 at 30 June 2026.
• The filing adds 3,564 shares of D.R. Horton, worth $580,504.

Compare institutions

          1
          Compare how Berkshire Hathaway, Tiger Global and Bridgewater changed their
        

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          Alphabet positions between their 13F filings for 31 March 2026 and 30 June
        

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          2026. Add up Class A and Class C where both are held. Show shares in both
        

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          quarters, the change in percent, the value at 30 June 2026 and the position's
        

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          share of each portfolio.
        

What comes back:

• Berkshire Hathaway: accession numbers 0001193125-26-226661 and 0001193125-26-352200. Tiger Global Management LLC: 0000919574-26-003362 and 0000919574-26-005427. Bridgewater Associates, LP: 0001350694-26-000002 and 0001350694-26-000003.
• In the same quarter that Berkshire Hathaway raised its Alphabet position by 48,144,587 shares, Tiger Global cut its position by 4,825,715 shares. Alphabet fell from 13.4 percent to 8.7 percent of Tiger Global's reported portfolio.

          1
          Which managers bought and which sold Micron Technology in the second quarter of
        

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          2026? Compare Coatue, Appaloosa and Bridgewater, and show the share count, the
        

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          value and the share of each portfolio in both quarters.
        

What comes back:

• Coatue Management LLC: accession numbers 0000919574-26-003501 and 0000919574-26-005478. Appaloosa LP: 0001656456-26-000002 and 0001656456-26-000003.
• Micron became Coatue's 3rd largest position, reported in 7 rows, and Appaloosa's 2nd largest position.
• Appaloosa's Micron value rose from $0.56 billion to $1.13 billion while its share count fell 41.4 percent. The share count shows the trade, and the value also reflects the price change.

FAQ

How do you track what hedge funds and institutional investors buy and sell?

Institutional investment managers with $100 million or more in section 13(f) securities, mainly US listed stocks and ETFs, report their long positions on Form 13F within 45 days after each quarter end. A comparison of two consecutive 13F filings shows new positions, exits and changes in share count. An AI assistant connected to 13F data through the SEC-API.io connector or plugin runs this comparison from a single prompt.

How often do institutional investors report their holdings?

Four times a year. Each 13F covers holdings on the last day of a calendar quarter and is due within 45 days: by 15 May for 31 March, 14 August for 30 June, 14 November for 30 September and 14 February for 31 December. When the deadline falls on a weekend or holiday, it moves to the next business day.

Did Berkshire Hathaway buy more Alphabet in 2026?

Yes. Berkshire Hathaway's 13F filings show 17,846,142 Alphabet shares at 31 December 2025, 57,835,013 at 31 March 2026 and 105,979,600 at 30 June 2026, across Class A and Class C. At 30 June 2026 the position was worth $37.76 billion. It was the third largest in the filing, after Apple and American Express.

What did Berkshire Hathaway sell in 2026?

In the first quarter of 2026, Berkshire Hathaway exited Visa, Mastercard, UnitedHealth Group, Domino's Pizza, Aon, Pool, Amazon and eight smaller positions. It cut Chevron by 35.2 percent, Nucor by 39.0 percent and Constellation Brands by 95.1 percent. In the second quarter, it sold the remaining Constellation Brands shares and reduced Capital One, Nucor, Kroger, Bank of America, Ally Financial and DaVita.

Does a 13F show short positions?

Form 13F covers only long positions in section 13(f) securities. SEC guidance tells managers to exclude short positions from the report and to report long positions without subtracting short positions. Written options are also excluded.

Does Form ADV show a fund's holdings?

Form ADV describes the investment adviser: regulatory assets under management, client types, fees, conflicts of interest and, in Schedule D, the gross asset value of each private fund. Position level holdings come from Form 13F for equity managers and from Form N-PORT for registered funds such as mutual funds and ETFs.

What is the difference between Form 13F and Form N-PORT?

Form 13F is filed by the investment manager and covers its long positions in US listed stocks, ETFs and certain options across all accounts at quarter end. Form N-PORT is filed for each registered fund, such as a mutual fund or ETF, and lists every position in that fund, including bonds and derivatives.

Can AI track institutional portfolios automatically every quarter?

An assistant connected to the SEC-API.io data runs the same prompt against each new 13F filing. For automated monitoring, the Form 13F holdings API returns new filings as structured data. A script or scheduled task then compares that data with the previous quarter.

Related reading

• MCP server documentation
• Get a free API key
• SEC: Frequently asked questions about Form 13F
• Form 13F institutional holdings API
• Form 13D and 13G API
• Form N-PORT API
• Form ADV API

Last updated: 17 September 2026. Educational content for general information about SEC filings, not investment advice.