Big options numbers versus activity that is genuinely unusual

Options activity is unusual when it breaks a contract's own pattern, not when the number attached to it happens to be large. Those two things get confused constantly, and the difference decides whether a flagged trade is worth a second look or is simply the market doing what it does every day.

A mega cap stock can trade an enormous number of contracts in a completely quiet session and none of it means anything, because that is a normal Tuesday for that name. A rarely traded contract in a mid sized company that usually sees a trickle and suddenly sees a flood is a different situation, even though the raw number is far smaller.

So the question a screen is really asking is not how big, but how big compared with what this contract normally does. That relative test is what separates genuine unusual options activity from a busy day in a busy name, and everything else follows from it.

Why absolute size is a poor filter

Ranking contracts by volume alone produces the same list most days. The biggest, most liquid names dominate it, because they always dominate it. Index products and the largest listed companies carry enormous options activity as a matter of routine, and a list built on absolute size mostly rediscovers that fact.

It also buries the cases worth noticing. Activity that stands out in a quieter name will never appear near the top of an absolute ranking, no matter how far outside its own norm it is. Sorting by size measures liquidity. It does not measure surprise.

What a screen is actually comparing

Screens that look for unusual activity work from a baseline drawn from the contract's own recent behaviour. The comparisons tend to be some mix of four things.

The first is today's volume against that contract's typical volume. A series that normally averages very little and then prints many multiples of its own average is unusual in a way a raw total cannot express.

The second is volume against open interest. Because open interest counts contracts that are still open while volume counts contracts traded today, volume that exceeds the standing open interest means more contracts traded than previously existed in that series, so at least some of the day's activity has to be new positioning rather than existing holders trading with each other.

The third is the size and shape of individual prints. A day's volume made up of one large block behaves differently from the same total assembled out of thousands of small orders, and screens often separate the two.

The fourth is time to expiry and distance from the current share price. Heavy activity in a contract far from the money with little time left has a different character from activity in a near term contract close to the share price.

Why the volume against open interest test gets so much attention

It is the one comparison that draws on how the plumbing works rather than on a statistical rule of thumb. The Options Industry Council explains that open interest only rises when both parties to a trade are opening, falls when both are closing, and stays put when one side opens and the other closes. The Options Clearing Corporation calculates the figure after the session, pairing opening and closing positions at the end of the day.

That timing is exactly why the test works and also why it needs care. The open interest quoted beside a contract during the day was struck after the previous close, so today's volume is being measured against yesterday's level. The comparison is still informative, but the confirmation only arrives the next morning, when the updated open interest shows whether those contracts were actually created or just passed around.

The false positives that fool a simple screen

A large share of flagged activity has a boring explanation. Three occasions produce most of it.

Earnings dates are the most common. Activity climbs into a scheduled announcement across both calls and puts, because people hedge and position around a known event. A screen with no calendar awareness reports this as a surprise every quarter.

Expiry is the second. Monthly contracts expire on the third Friday, and the days around it carry activity that is about closing or rolling positions rather than new conviction. FINRA notes that the majority of American style exercises and assignments happen on or near the contract's expiration. The days around those dates are thick with closing trades and with rolling, where an investor shuts a position in one expiry and opens a similar one in the next. The tape looks busy. The intent is maintenance.

Index changes are the third. When an index provider adds or removes a company, funds tracking that index have to trade to match, and the options market around the name moves with it on a schedule that is published in advance. The same goes for other corporate events like takeovers and spin offs, where FINRA observes that shares becoming difficult to borrow because of a pending corporate action can itself prompt early exercise.

Beyond the calendar, there is the everyday reality that the counterparty to a large trade is often a market maker managing inventory rather than an investor with a view, and that a multi leg strategy prints in several contract series at once. A screen counting each leg separately reports one trade as several.

What a flag can and cannot tell you

A flag tells you where to look. It says a contract behaved unlike itself, on a particular day, in a particular direction of the options market. That is a starting point for a question, not an answer.

What it cannot tell you is who traded, why, or whether the trade was bullish at all. Public options data reports contracts by series, not identities or intentions, and as covered in call and put volume, a put buyer may be protecting shares and a call seller may already own them. Unusual activity is a description of behaviour in a contract. Any story attached to it is supplied by the reader.

This is also why it is worth seeing next to other things rather than on its own. A contract behaving oddly in a company where directors have also been filing purchases is a more interesting fact pattern than the same reading in isolation, which is the thinking behind how the InsiderPulse score works.

How InsiderPulse handles this

Options Flow shows options activity alongside SEC Form 4 insider filings, US congressional trade disclosures, dark pool and volume data, prices and news, so a flagged contract is never the only thing on the screen. Options data is one of several inputs to the 0 to 100 score rather than the score itself. Ask Pulsey can answer questions about what sits behind a reading with citations to the source data. Coverage is US listed stocks and ETFs plus crypto, forex and commodities, and ASX shares are outside it.

InsiderPulse is a data tool. Nothing on this page is financial advice.