Narration: AI voice.
One row, two clocks
QQQ calls expiring October 16, 2026. 2,334,975 contracts of volume, against 172,527 contracts of prior open interest. 13.5 times. That's one line of the volume against open interest table on the options flow hub, as of Oct 16, 2026, 13:16 ET. Big number. Easy to misread. Volume and open interest run on two different clocks, and the ratio between them says less than it looks like. Here's what it can tell you, and what it can't.
Two counts
Definitions first. Volume counts every contract that changes hands during the session, whether that trade opens a position or closes one. It resets to zero every morning. Open interest counts contracts still outstanding: opened, and not yet closed, exercised or expired. The clearinghouse, the OCC, counts it once a day after the close and posts it before the next open. One is a flow. The other is a stock. Volume climbs all day. Open interest sits at the prior settlement figure all day, however much trades, and moves only when the next count lands. So open interest on any screen describes a prior close. On the flow hub, the column header says it outright: prior open interest.
Why same-day volume dwarfs open interest
Now look at the expiry on that row. It expires the same day it traded. That is a large part of why the ratio runs so high. A same-day contract opened at 9:45 and gone by the close is created and extinguished inside one session, so it never sits in any overnight count. The series still carries whatever open interest it built on earlier days. So the denominator is a fixed figure from yesterday's settlement, and the numerator is every contract that changed hands today: opening, closing, and turning over again.
Activity against the standing book
So what does volume over prior open interest measure? New activity against the standing book. Nothing more. Every trade is one of three cases. Both sides opening: open interest rises by one. Both sides closing: it falls by one. One side opening, the other closing: the contract changes hands and the count doesn't move. A single trade on the tape doesn't say which case it was. Only the clearing records, netted after the close, can. So a ratio of 13.5 times says the session's activity was large next to the standing positions. It does not say positions grew. The hub says the same thing in its limits. Session totals, not trades: volume is read from chain snapshots and added up by ticker, expiry, and call or put. A chain can't say which side anyone was on, whether a contract was opened or closed, or whether it was one leg of a spread. Calls can be sold. Puts can hedge stock. So no row carries a direction. Premium is an estimate, volume times the quote midpoint times a hundred shares, and it's labelled est. wherever it appears. Coverage is a window: 21 symbols intraday, up to 40 strikes around the money per expiration, or every strike in the nearest expirations. The strikes tracked, not the full book. And any cell under three traded contracts is withheld.
The follow-up
That leaves one honest way to learn what stayed open: wait for the next count. On the hub, every snapshot gets a follow-up. After the next settlement, the snapshot page adds the open interest change for the same contracts. After expiry, it adds where the underlying settled against the strike. Written the same way, whatever the outcome. Same page, further down: open interest that rose at the latest settlement, Oct 15, 2026. SPY puts expiring October 19, 2026, up 201,858 contracts, to 295,806. That's a count of positions open at a close. It's still a net number, and the line under the table says what it can't do: it does not say which side opened or closed.
The overnight change pages
For the wider view there's the overnight change page. It compares two settlements, October 15 against October 14, from SquawkFlow's own nightly archive of Cboe settled open interest: 212 symbols on this pair. Figures are contracts, not dollars. Net change across all of them: +6,123,360 contracts. Calls netted +3,013,909, puts +3,109,451. The page's caveat, word for word: open interest change, not trades; it does not say which side opened or closed. And the morning after an expiration, whole series leave the count because they ran out of time, not because anyone closed them. For SPX alone, the overnight change page nets it out between two completed settlements: calls up 250,274 contracts, puts up 478,692. A build is a count. It isn't a direction.
What none of it tells you
So, the checklist. Volume is the session total. Open interest is the prior settlement. The ratio is new activity against the standing book, and on same-day expiries it runs huge by construction. The next count is the only way to know what stayed open, and even that is a net number. None of it tells you the side, whether a contract opened or closed, whether it was a spread leg, or what anyone paid. How the overnight count is built is on the learn page linked below. Educational only.
Full write-up with sources: /learn/when-does-open-interest-update
Educational content, not investment advice.
Levels shown are as captured on 2026-10-16 13:35 ET; they are not current.