Methodology

BaryCenter classifies each option print against the quote that preceded it. A print at or above the ask is a buy; at or below the bid is a sell; inside the spread is unclassified and does not enter buy/sell totals.

Premium is size × price × contract multiplier. Call and put ratios are buy-premium divided by sell-premium in the selected window. Net premium can be negative when selling dominates.

Timeframes of 1m–1h are wall-clock lookbacks. 4h and 8h, and the −Nd day windows, walk back across prior exchange sessions (weekends and holidays skipped). Extended-hours prints inside the resulting interval are included when the feed has them.

The browser never receives raw prints — only aggregated ladders. That is both a performance choice and a data-handling constraint.