Data quality
Sources & methodology
All data is sourced from public filings and market data providers. Below is a summary of what I use, how I process it, and where limitations apply.
Holdings data · 13F filings
Institutional Investment Managers with ≥ $100M in qualifying assets are required to file quarterly.
13F filings only cover securities on the SEC's official list. Non-US holdings, private equity, bonds, options, and cash are not reported.
Managers have 45 days to file after each calendar quarter closes. I check EDGAR daily and process filings as they appear.
When a manager files an amended 13F (13F-HR/A), I use the amended version and ignore the original.
Values are reported by the manager in thousands of USD, based on prices at the last trading day of the quarter.
Price data
Adjusted closing prices for the trailing 5 years.
Prices are available for NYSE, NASDAQ, and NYSE American-listed securities regardless of the company's country of incorporation. True foreign private issuers (20-F filers) with no US-listed shares are excluded.
Each security's CUSIP is mapped to a ticker via the OpenFIGI API. If no US-exchange result is found, I validate any available ticker with yfinance. A small manual override list covers the rare CUSIPs OpenFIGI does not recognise.
Used to estimate current position value and unrealized gain/loss. Prices are not real-time — typically delayed by one trading day.
Estimated average cost
When a position is opened or increased, I use the average daily closing price of that quarter as the estimated cost. On subsequent top-ups, the cost basis is recalculated as a weighted average of shares held and new shares added.
I do not extrapolate or assume a cost for positions opened before my price data window. These show as N/A.
The actual cost paid by the manager is not disclosed in 13F filings. My estimate is a reasonable approximation but will differ from reality.
10-K company data
Filed by US-listed companies annually. I extract Items 1, 1A, 7, and 8 (Business, Risk Factors, MD&A, Financial Statements).
Companies that report to the SEC as foreign private issuers file Form 20-F instead of 10-K — those are not included. This affects some ADRs even if they are large, widely-held names.
The AI Overview tab summarises 10-K content using a large language model. It is not financial advice and may contain inaccuracies. Always refer to the original filing.