⏱ 1-Minute Summary A T-1 closing snapshot is a single, complete picture of the options and stock market captured at the previous trading day's close. Each snapshot contains the closing price, implied volatility (IV), historical volatility (HV), open interest, volume, and the full set of Greeks for every option. It is one static point per day, not a real-time stream.
1. What Is a T-1 Snapshot?
T-1 means the data is captured at the market close of the previous trading day. After the US market closes, we take a complete snapshot of every symbol and every option contract at that exact moment.
This is end-of-day (EOD) data: one consistent, standardized point per trading day. There is no 1-minute, 5-minute, or 15-minute data: just a clean, daily picture you can backtest over years.
What Is Inside Each Snapshot?
Every snapshot contains the following fields for each option and its underlying:
- Closing price: the final trade or settlement price of the underlying at market close.
- Implied Volatility (IV): the market's forward-looking expectation of future volatility, backed out of option prices.
- Historical Volatility (HV): the realized volatility of past returns over a lookback window.
- Open Interest (OI): the total number of outstanding option contracts for a given strike and expiry.
- Volume: how many contracts traded that day.
- The full set of Greeks: Delta, Gamma, Theta, Vega, Rho: measuring how the option's price responds to changes in price, time, and volatility.
2. When Is the Data Updated?
The update schedule matters if you build around daily signals:
- The platform finishes cleaning and validating all data and goes live 3 hours before US market open.
- Weekends and US public holidays: no data updates. After consecutive holidays, all missing daily snapshots are backfilled on the first trading day after the break.
This gives you a consistent, gap-free daily series; exactly what long-term backtesting needs.
3. Snapshot vs Real-Time Stream: A Fundamental Difference
| T-1 Closing Snapshot | Real-Time Stream | |
|---|---|---|
| Frequency | Once per trading day | Continuous / minute-level |
| Content | Closing price + closing IV/HV/OI/volume/Greeks | Every tick or bar |
| Purpose | Daily-frequency backtesting, long-term research | Intraday timing, scalping, event trading |
| Noise | Low (one point, no microstructure noise) | High (bid/ask bounce, print timing) |
A snapshot removes intraday noise, the random bid/ask bounce and short-term microstructure that can distort a long-term view. What you lose is the ability to study the path the price took during the day, which is exactly the data a long-term trader does not need.
⚠️ Platform Data Boundary: This platform provides T-1 EOD closing snapshots only. This design is intentional: it is the correct data for multi-day-to-multi-month long-term strategy research and backtesting. It is not intended for intraday, 0DTE, or earnings-event strategies, which require path data that EOD snapshots cannot provide.
⚠️ Research Use Only: This article is educational. Understanding a data field is not a trading signal. Use this platform's T-1 data and backtests as historical statistical reference only; past performance does not guarantee future results.