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Rolling vs Fixed Strike Selection

When your strategy runs indicators on option data - a single option chart or several options combined. Signals AI has to answer one question on every candle:

Which exact option contract do I calculate the indicator on right now?

Strike Selection Timing answers it, and it has two modes:

  • Rolling - re-pick the strike whenever your criteria say a different strike now qualifies. The contract can change during the day.
  • Fixed - pick the strike once, at a time you set, and use that same contract for the rest of the day.
The one thing to remember

Rolling vs Fixed is only about when the strike is chosen. The strike criteria (ATM, ITM/OTM offset, Premium Range) are exactly the same in both modes.

What a "strike" actually means​

Picking a strike fixes all of these together into one tradable contract:

PartExample
UnderlyingNIFTY
Option typeCE / PE
ExpiryWeekly / Next Weekly / Monthly / Next Monthly
Strike priceSet by your Strike Criteria (e.g. ATM)

The result is one contract - e.g. NIFTY 24000 CE (weekly) and your indicators are calculated on that contract's candles.

Rolling​

Under Rolling, Signals AI re-checks your strike criteria on every candle. If the criteria now point to a different strike, the strategy switches to the new contract and keeps evaluating your indicators on it.

How it behaves:

  1. On each candle, resolve the strike from your criteria and the current spot/premiums.
  2. Calculate the indicator on whichever contract is currently resolved.
  3. Evaluate your entry/exit conditions on that value.

Because the contract can change through the day, the series your indicators run on is a composite - segments of different strikes joined at the moments the strike rolled.

Use Rolling when you always want to be looking at "the current ATM/OTM option" as spot moves - the relationship to spot matters more than staying on one contract.

Rolling can't be matched to a single chart

Because the contract switches mid-day, an indicator's lookback will, right after a roll, be reading candles from a different contract than a few candles earlier. That's expected, but it means the series is not one real chart you can pull up on a broker or TradingView and match candle for candle.

Fixed​

Under Fixed, Signals AI resolves the strike once, at the fix time you set (e.g. 09:16 or 09:20), using your criteria and the spot/premiums at that moment. That single contract is then used for every entry/exit check for the rest of the session. The strike does not move as spot moves.

How it behaves:

  1. At the fix time, resolve one strike and lock it for the day.
  2. For the rest of the day, calculate indicators on that one contract's candle series.
  3. Indicators like RSI and EMA need candles from before today's session (their lookback period). Under Fixed, Signals AI pulls that history from previous days - but each previous day used its own, different fixed strike.
The single-strike rule

Under Fixed, the strike is chosen once at the fix time and every entry/exit check that day runs on that single strike. But indicators like RSI and EMA need candles from before today's session, and Signals AI pulls that lookback history from previous days where each day used its own, differently selected fixed strike. So the series an indicator actually runs on is stitched together from several different contracts across days, not one continuous option. This is why a Fixed strike signal cannot be reproduced candle for candle on TradingView or your broker, and why it can differ from what a single option's chart would show.

Before the fix time: no strike is resolved yet, so no entries can fire before then. Set time-based entries at or after your fix time.

Use Fixed when you want an intraday, single-strike strategy - you pick a strike in the morning and trade only that strike for the day.

On the Options chart vs the Combined Premium chart​

The strategy evaluates indicators on the premium of one option (CE or PE).

  • Rolling: the single evaluated option can change strike intraday.
  • Fixed: one option is chosen at the fix time and evaluated all day.

Indicators run directly on the option premium, which is driven by the underlying move plus time decay (theta) and volatility (IV). So, signals differ from spot/futures charts.

Worked examples​

All examples use NIFTY, weekly expiry, 5-minute candles, with this spot path during the day:

TimeNIFTY spot
09:2024,000
11:0024,060
13:0024,110
14:3024,180

ATM CE, fix time 09:20.

  1. 09:20 - resolve once. Spot 24,000 → ATM CE = 24000 CE. Locked for today.
  2. All day - RSI 14 / EMA 20 run on 24000 CE's premium for today's candles. But their lookback (candles from before today) is pulled from previous days - which each used a different fixed strike (e.g. yesterday's ATM was 23950 CE, the day before 24100 CE).
  3. Spot rises to 24,180, but today's evaluated contract stays 24000 CE (now deep ITM). Conditions today are only ever checked on 24000 CE.
  4. Verify: because the lookback spans those different daily strikes, opening NIFTY 24000 CE on TradingView will not reproduce the indicator values candle for candle. Fixed is not externally verifiable this way.