ptolemy

Essays on the data layer behind fundamental finance — how SEC filings, market data, and corporate actions turn into numbers you can screen, rank, and backtest without lying to yourself.

Most financial metrics look like simple arithmetic. Revenue divided by shares. Price times float. Enterprise value minus cash. The hard part is not the formula. It is deciding which objects the formula is allowed to combine, at which timestamp, under which accounting definition, and with which restatement history removed.

This site treats those constraints as database problems: point-in-time snapshots, typed identities for issuers and listings, versioned financial statements, and screeners that must stay fast while staying correct.

He is lead developer of DollarFlow, a stock screener built around those ideas.

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