Equity Options: subscriptions and chain data — QuantConnect / LEAN

Two decisions shape every equity-options algorithm, and each has two answers that look interchangeable but carry different data: how you subscribe (AddOption vs AddOptionContract) and how you read the chain (the slice's OptionChains vs the OptionChain() method). Picking the wrong member of either pair produces algorithms that trade on day-old numbers without any error.

Greeks/IV freshness — the core rule

There are two different option datasets behind the APIs (doc: "There is a daily, pre-calculated dataset based on the end of the previous trading day. There is also a stream of values that are calculated on-the-fly as your algorithm runs."):

The operating rule that follows: any intraday decision — entry sizing, delta hedging, IV-threshold checks, strike selection at a decision time — should read the slice's chain. The OptionChain() method is for daily contract discovery (find which contracts exist, filter by prior-day delta/OI, then subscribe); using it for intraday sizing or greeks means every number is one day stale, and nothing errors to tell you. Greeks on slice contracts are computed lazily — accessing Greeks costs nothing; accessing Greeks.Delta triggers the calculation — so only read the greeks you need.

Pick ONE route — and subscribe only what the strategy can trade

Decide the route once, in Initialize. Mixing them is usually a smell:

• Universe route (AddOption + filter): a universe's purpose is its slice chain. If all selection, pricing, and sizing happen through OptionChain() anyway, the minute-resolution subscriptions are pure cost — either read the slice for the decisions that need live data, or drop the universe and subscribe the picks directly.
• Discovery route (OptionChain() + AddOptionContract): the daily chain picks the contracts; subscribe each pick. Match the data to the decision: the OptionChain() rows are previous-close values — fine when daily-granularity data suits the strategy (screening, ranking, a daily-cadence rule that tolerates day-old marks), but when the strategy calls for decision-time values (intraday sizing, hedging, entry marks), read the subscribed picks' live quotes from the slice. Whichever you use, know which one you are using.
• A subscription earns its cost by being read or being held: a contract you own needs its subscription (position pricing, fills, expiry processing) even if you never read a chain. What doesn't earn its cost is breadth — a wide AddOption universe where the algorithm neither reads the slice chain nor holds more than its few picks.
• OptionChain() needs no option subscription — the underlying's equity subscription is sufficient. Never add AddOption, a filter, or AddUniverseOptions just to make a chain available; an empty chain has some other cause.

Size the subscription to the trade, not to the chain:

• Prefer a strategy-shaped filter when one matches the structure — u.IronCondor(30, 5, 10), u.Straddle(30), u.CallSpread(30, 5), and friends subscribe only the legs the strategy needs.
• Otherwise derive the strike span and DTE window from the structure's own numbers (target deltas, wing widths, expiry rules), adding a delta-band filter (u.Delta(0.05m, 0.30m)) where the structure is delta-targeted. The span should be the tightest one that always contains the tradable candidates — not a safety blanket.
• Strikes(-100, 100), or an unfiltered Expiration(0, 500) window, subscribes thousands of minute-resolution contracts — a cost bug even when the algorithm is otherwise correct.

Subscription route 1: AddOption — a filtered basket (universe)

For strategies that pick contracts from a chain at decision time (spreads, condors, straddles, rolling structures), subscribe once in Initialize:

UniverseSettings.Asynchronous = true;
var option = AddOption("SPY");                  // underlying auto-subscribed RAW
option.SetFilter(u => u.IncludeWeeklys().Strikes(-3, 3).Expiration(15, 60));
_symbol = option.Symbol;                        // canonical Symbol — save it

• The canonical option.Symbol is not tradable — it is the key into data.OptionChains and the first argument of every OptionStrategies factory.
• Filter timing: selection "usually runs at the first bar of every day"; a newly selected contract's data arrives "in the next Slice". So the chain can be absent on any given event — always guard: if (!data.OptionChains.TryGetValue(_symbol, out var chain)) return;.
• Default filter if you never call SetFilter: standards + weeklys, within 1 strike of the underlying price, expiring within 35 days — almost never what a spec wants; set the filter explicitly.
• Filter building blocks: Strikes(min, max) (relative strike counts around the money, not dollars), Expiration(minDays, maxDays), CallsOnly()/PutsOnly(), WeeklysOnly()/StandardsOnly()/IncludeWeeklys(), FrontMonth()/BackMonth(), greek/OI filters Delta(min, max), IV(min, max), OpenInterest(min, max) (these compare prior-day EOD values — use them for coarse pre-selection, then pick precisely from live slice greeks), and strategy-shaped helpers (u.Straddle(30), u.IronCondor(30, 5, 10)) that narrow the universe to exactly the legs a named strategy needs.
• Resolution rule: the option resolution must be ≥ the underlying Equity's resolution (minute equity → minute/hour/daily options). Contract subscriptions support minute, hour, and daily; minute is the default.

Reading the chain at a decision time:

public override void OnData(Slice data)
{
    if (!data.OptionChains.TryGetValue(_symbol, out var chain)) return;
    var spot = chain.Underlying.Price;
    var atmCall = chain.Where(c => c.Right == OptionRight.Call)
        .OrderBy(c => Math.Abs(c.Strike - spot)).First();
    var delta = atmCall.Greeks.Delta;    // live price-model value, computed on request
    var mid = (atmCall.BidPrice + atmCall.AskPrice) / 2;
}

In a Scheduled Event there is no slice parameter — read the same object through CurrentSlice.OptionChains.

Subscription route 2: AddOptionContract — individual known contracts

For strategies that hold a few specific contracts found by daily screening, discover with the OptionChain() method, then subscribe each pick:

// In a scheduled event — OptionChain() carries PRIOR-DAY EOD greeks: fine for
// discovering contracts, wrong for intraday sizing or hedging.
var chain = OptionChain(_underlying);
var expiry = chain.Min(c => c.Expiry);
var symbol = chain
    .Where(c => c.Expiry == expiry && c.Right == OptionRight.Call && c.Greeks.Delta > 0.3m)
    .OrderBy(c => c.OpenInterest).Last().Symbol;
AddOptionContract(symbol);

The three idioms that must accompany this route:

1. Seed prices — a contract subscribed this time step has no data until the next slice ("you'll need to wait until the next Slice to receive data and trade the contract"). Set Settings.SeedInitialPrices = true; in Initialize to trade it immediately.
2. RAW underlying — subscribe the underlying with AddEquity("SPY", dataNormalizationMode: DataNormalizationMode.Raw) so strike-vs-price comparisons share a scale. If you skip this, LEAN auto-subscribes (or force-switches an existing subscription) to RAW anyway — see the history caveat below.
3. Volatility warm-up — SetWarmUp in Initialize cannot anticipate contracts added later; warm the underlying's volatility model in a security initializer (feed ~30 daily bars through security.VolatilityModel.Update(...)) so slice-chain IV/greeks are sane from the first read. On the AddOption route the simple SetWarmUp(31, Resolution.Daily) suffices (default volatility model needs 30+1 daily bars).

To read a subscribed contract from the slice, index the chain with the canonical: data.OptionChains.TryGetValue(_contractSymbol.Canonical, out var chain). RemoveOptionContract(symbol) cancels its open orders and liquidates the position.

The RAW-underlying history caveat

Because any option subscription forces the underlying Equity to RAW normalization, a History() call on that underlying now returns raw closes — dividend gaps included. Any realized-volatility, daily-return, or overnight-gap calculation on an option underlying must request adjusted data explicitly: History(_underlying, 22, Resolution.Daily, dataNormalizationMode: DataNormalizationMode.Adjusted). Do not "fix" this by subscribing the underlying ADJUSTED — LEAN silently switches it back to RAW.

Common mistakes

• Sizing or hedging from OptionChain() intraday. Its marks and greeks are the previous close; position sizes computed from them are provably off versus decision-time quotes. Decision-time numbers come from the slice's chain.
• Trading the canonical symbol, or passing a contract symbol where the canonical is required (chain lookup, OptionStrategies factories).
• No TryGetValue guard — the chain is legitimately absent before the first daily selection and whenever the filter turns over.
• Forgetting IncludeWeeklys() when a spec's DTE window (e.g. 21–45 days, closest to 30) needs weekly expiries to hit its target.
• Carrying a wide universe you never read — subscribing a broad chain while doing all selection, pricing, and sizing through OptionChain(): every subscription beyond the contracts actually held is pure cost. Read the universe's slice chain for the decisions that need live data, or drop the universe and use AddOptionContract on the picks.
• Subscribing a huge chain as a tradability crutch (±100 strikes, unbounded expiries) so any discovered contract can be ordered directly — subscribe the picks with AddOptionContract instead, and let a strategy-shaped or structure-derived filter keep the universe minimal.
• Computing RV/returns on the force-RAW underlying without an explicit adjusted-normalization history request.
• Only American-style US equity options are supported; strikes in the filter API are relative counts, not dollar offsets — Strikes(-1, 1) means one strike either side of the money.