S&P 500 Index (SPX) Open Interest History

Open interest tracks the total number of outstanding options contracts. Rising OI alongside price moves can indicate growing commitment to the trend; declining OI suggests positions are being closed.

Snapshot as of Aug 21, 2026.

Spot Price

$7683.27

Call OI

9.4M

Put OI

13.3M

Total OI

22.7M

Put/Call Ratio

1.12

As of Aug 21, 2026, S&P 500 Index (SPX) has 22.7M total contracts outstanding across all expirations. Put/call OI ratio is 1.42 (put-heavy positioning, often indicating hedging or bearish bias). Open interest reflects accumulated positions from prior sessions; persistent growth indicates sustained directional or hedging interest, while sharp drops typically mean post-expiration clean-up.

How SPX open interest history Data Feeds Strategy Selection

Strategy selection on S&P 500 Index options does not derive from any single metric in isolation. The open interest history view above sits inside a broader read: ATM IV currently sits at 12.2% and dealer gamma exposure is positive, so dealer hedging is mechanically mean-reverting. Combine the open interest history data here with the volatility-skew surface, dealer-gamma exposure, max-pain level, and upcoming-events calendar to build a positioning thesis. Risk-defined structures (credit spreads, debit spreads, iron condors) are usually safer than naked positions while the regime is uncertain; the data on this page anchors the inputs but does not by itself constitute a trade thesis.

How to read the SPX open-interest data

The open-interest time-series above tracks the total S&P 500 Index options inventory outstanding day by day. OI is a stock measure - the cumulative position count - so trends flag accumulating or distributing positioning. Current put/call ratio is 1.12, roughly balanced. Total call OI of 9.4M versus put OI of 13.3M gives a put/call OI ratio of 1.42 - structurally a slower-moving signal than the volume-based ratio.

SPX flow vs positioning

Volume tells you what flows happened today; OI tells you what positions accumulated. Both can move in opposite directions: rising volume with falling OI means contracts are being closed (covering); rising volume with rising OI means new positions are being opened. The combination matters more than either alone for reading sentiment. Combined with the current positive dealer-gamma regime, large OI clusters tend to act as price magnets through expiration cycles.

Using SPX OI/volume data alongside other surfaces

Per-strike OI is the input to dealer-gamma calculations: strikes with elevated call OI generate gamma walls that dealers must hedge into as spot approaches them. The gamma-exposure page combines this distribution with the dealers' assumed-long-gamma assumption to project hedge flow. Volume cross-checks recent positioning shifts in the chain that haven't yet shown up in cumulative OI. Pair both with the term-structure view on the volatility page to determine whether the activity is concentrated in near-dated event hedging or longer-dated structural positioning. Front-month expiration for SPX sits at 31 days, so near-dated volume currently dominates the flow reading.

Learn how open interest is reported and how to read the data →

Daily open-interest history for SPX options over the last ~33 trading days. Each row reflects the end-of-day total OI summed across all listed strikes and expirations.

Most recent 15 trading days (descending). Older history appears in the chart above.

Frequently asked SPX open interest history questions

What is the current SPX options open interest?

As of Aug 21, 2026, S&P 500 Index (SPX) has 22.7M total contracts outstanding across all listed expirations, split as 9.4M calls and 13.3M puts. Open interest reflects accumulated positions from prior trading sessions; it does not include today's volume until end-of-day reconciliation.

What is the SPX put/call open interest ratio?

Put/call OI ratio of 1.42 is put-heavy, often indicating hedging demand or bearish positioning.

What does SPX open interest tell traders?

Persistent OI growth indicates sustained directional or hedging interest; sharp drops typically mean post-expiration position cleanup. Heavy OI concentrations at specific strikes act as support and resistance levels because dealer hedging amplifies near those strikes - the gamma profile of the dealer book is concentrated there. Comparing today's volume to standing OI separates opening flow from closing flow.