Four comparisons answer different questions
A large daily volume is a count of contracts traded, not one large order. The same position can trade several times. Start with an exact contract: underlying, call or put, strike, expiry and any adjusted deliverable. A stock-volume spike and an option-series volume spike are different observations.
| Comparison | Calculation | What it establishes |
|---|---|---|
| Relative historical volume | Session volume / mean volume in prior sessions | Activity relative to a chosen window. Use the same contract and session cutoff; exclude the session being measured. |
| Volume / open interest | Session volume / prior trading-day OI | Turnover relative to outstanding contracts. This is not relative historical volume. |
| OI change | Next reported OI minus prior OI | Net change across the entire series after processing. It cannot assign opening or closing status to an individual print. |
| Quoted spread | (Ask minus bid) / ((ask plus bid) / 2) | Quoted transaction friction at that observation time. Check quote size and freshness before assuming execution. |
The scanner's default 2x Vol/OI threshold is a filter setting, not a statistical significance level. Low OI can inflate a ratio. Contracts with zero or missing OI are excluded because their ratio is undefined; that exclusion does not mean they have no unusual trading. Newly listed or adjusted contracts may lack a useful historical baseline. Earnings, expiry and rolls can change the normal activity pattern.
A 6,000-contract day does not mean 6,000 new bets
Hypothetical completed session: an XYZ 100 call trades 6,000 contracts. Its preceding 20-session average is 1,200, prior OI is 2,000 and the next reported OI is 2,600. Relative volume is 6,000 / 1,200 = 5x; Vol/OI is 6,000 / 2,000 = 3x; the OI change is only +600 contracts. These are compatible observations. Opening, closing and transferred positions can coexist during the day.
At a hypothetical $2.10 bid and $2.30 ask, the quoted spread is $0.20 per share. The midpoint is $2.20, so spread / midpoint is 9.09%. A 1,000-contract print at $2.30 with a standard 100-share multiplier has $230,000 gross premium (1,000 × 100 × $2.30), before fees. That is premium exchanged, not the trader's total portfolio risk or a verified bullish allocation. Adjusted contracts can have different deliverables.
Prints need context that a snapshot cannot supply
A call purchase can hedge a short stock position; a call sale can be one leg of a spread. A put purchase can be insurance. A roll can create a closing trade in one expiry and an opening trade in another. Even a print near the ask is only consistent with an aggressive buyer if the quote is synchronized and the trade conditions support that interpretation. A later snapshot quote cannot establish the quote at execution.
OIC explains that OI rises when both counterparties open, falls when both close, and stays unchanged when a position transfers between them. Clearing, exercises and assignments also matter. Next-day OI helps test a hypothesis about the series, but it does not reveal the identity or complete strategy behind a selected trade.
Keep an evidence record before choosing a direction
- Scan a small ticker list, then record the full contract symbol and the volume and OI cutoff. This page requests the first 250 contracts per ticker, so absence from results is not a full-chain finding.
- Check the daily-bar and quote timestamps. A successful refresh records fetch time; it does not make an old quote current. Missing quotes, market closures and provider permissions can limit the evidence.
- Use the worksheet with a separately sourced historical baseline and the subsequent OI report. Save the contract, date, source and calculations as JSON. Its example inputs are not market data.
- In Market Insights, inspect available Options Flow alert details, contract type, size, premium and trade times. Compare any side classifications with synchronized quotes from your data source; labels do not prove opening status.
- Write the unresolved alternatives, such as a spread, hedge or roll, alongside the directional hypothesis. Check current executable quotes and position risk independently.
Educational research only. Options can lose their entire premium; short positions can have larger losses. This scanner does not recommend trades or predict returns.
Sources and data definitions
Reviewed October 21, 2026. Provider fields and quote access can change.