Option strategies and the option lifecycle — QuantConnect / LEAN

Placing multi-leg positions: two documented routes, no third

Route A — OptionStrategies factory + Buy. One call builds the whole structure from the canonical option symbol (saved from var option = AddOption(...); _symbol = option.Symbol;) plus strikes/expiries — no contract symbols needed, all legs placed atomically:

var strategy = OptionStrategies.IronCondor(_symbol, farPut, nearPut, nearCall, farCall, expiry);
Buy(strategy, 2);         // 2 condors; Sell(strategy, q) inverts every leg

Both directions of every structure have their own factory (Straddle / ShortStraddle, IronCondor / ShortIronCondor) and a "short_" factory is still placed with Buy. The catalogue (PascalCase members of OptionStrategies): bear/bull call/put spreads; long/short call/put butterflies (strike order higher, ATM, lower); long/short call/put calendar spreads ((strike, nearExpiry, farExpiry)); covered/naked/protective calls and puts; protective collar; conversion/reverse conversion; long/short straddles and strangles; long/short iron butterflies and iron condors (strikes ascending); long/short box spreads; long/short jelly rolls; bear/bull call/put ladders; long/short call/put backspreads. Covered/protective/conversion structures embed the underlying — buying one unit of CoveredCall is long 100 shares + short 1 call.

Route B — combo orders. Build Leg.Create(symbol, ratio) lists from actual contract symbols when you need custom ratios, a leg set no factory matches, or limit pricing:

var legs = new List<Leg> { Leg.Create(shortCall.Symbol, -1), Leg.Create(longCall.Symbol, 1) };
var tickets = ComboMarketOrder(legs, quantity);        // one ticket per leg

• Leg quantities set the ratio; the order's quantity argument is a global multiplier and sets the combo's direction. At least one positive and one negative leg; each leg a unique contract.
• ComboLimitOrder(legs, quantity, limitPrice) — one net price for the package, legs fill together when the combined price crosses it; the only combo type documented to also accept an underlying-equity leg. ComboLegLimitOrder — per-leg limits via the third argument of Leg.Create; each leg fills on its own limit. Both are updatable through the leg tickets until filled.
• Combo orders are synchronous by default with a 5-second wait (extend via Transactions.MarketOrderFillTimeout); pass asynchronous: true to fire-and-continue. Marketable combos on illiquid OTM contracts "may take a few minutes to fill".

There is no route C. Legging into a multi-leg structure with sequential single market orders is not a documented pattern: it carries leg risk (partial structures during fills) and the interim one-sided position can fail margin that the complete structure would pass. Single-leg strategies (naked call/put) are the one case where a plain MarketOrder is the documented approach.

Margin: recognized structures are cheaper

LEAN groups positions that compose a recognized strategy and margins the group, not the legs — the docs' example: an ITM long call ($29,150) plus an OTM short call ($101,499) margin at $130,649 separately but $0 as a bull call spread. Defined-risk structures (spreads, condors, butterflies) are therefore dramatically cheaper than their leg-sums; don't pre-reject a trade by summing per-leg requirements. For a pre-trade check, wrap the strategy in new OptionStrategyPositionGroupBuyingPowerModel(strategy) and query GetInitialMarginRequirement(...) against Portfolio.MarginRemaining (the result is per one unit — multiply by your quantity).

Early assignment: an hourly simulation you must expect

Short American options in a backtest can be assigned before expiry. The default DefaultOptionAssignmentModel scans hourly and assigns a short option that is within 4 days of expiry, at least 5% in the money, and profitable to exercise after fees (European style: expiry day only). Any strategy holding short legs into that window (covered calls, short condors near expiry, diagonals) must handle assignment — or, when the strategy's rules exit before the window (e.g. manage-at-21-DTE), assignment simply never triggers. To disable the simulation deliberately: (security as Option).SetOptionAssignmentModel(new NullOptionAssignmentModel()); in a security initializer.

Handle assignment in OnAssignmentOrderEvent — not by sniffing IsAssignment in the generic order-event handler. The docs' working examples read the just-delivered share position inside the dedicated handler (holdings are current there) and clean up immediately:

public override void OnAssignmentOrderEvent(OrderEvent assignmentEvent)
{
    var shares = assignmentEvent.Quantity * _option.SymbolProperties.ContractMultiplier;
    MarketOrder(assignmentEvent.Symbol.Underlying, -shares, tag: "Assignment cleanup");
}

Reacting from the generic OnOrderEvent instead has been observed to fire before the delivered shares are booked, so a holdings-based cleanup silently does nothing until a later event. Note the delivered shares appear at the strike price via a fill event, simultaneous with a zero-price fill that removes the option contract; assignment after the close cannot be flattened until the next session's open regardless of handler.

Expiry: LEAN acts on the contracts, not on your state

At expiration LEAN auto-exercises long ITM positions ("Automatic Exercise": zero-price fill removing the contract + a strike-price fill delivering the underlying for physical settlement) and removes OTM contracts worthless. None of your exit logic runs. Any strategy that tracks its own open position (a self._position object, leg symbol fields) must clear that state when contracts expire — otherwise the algorithm believes a position is still open, its management checks keep early-returning on missing data, and it silently never trades again. If the strategy's rules are supposed to exit before expiry, treat reaching expiry as a bug signal, but still write the state-cleanup path. Manual exercise: ExerciseOption(contractSymbol, quantity) — long positions only, American any time, European only at expiry, rejected on insufficient capital.

Common mistakes

• Selling a short_* factory (double inversion) — short factories are bought; Sell on the long factory is the other spelling of the same trade.
• Butterfly strike order: all four butterfly factories take (higher, ATM, lower) — the doc examples' variable names disagree with their own math; follow the order, not the names.
• Passing the underlying Equity symbol or a contract symbol as a factory's first argument — it must be the canonical option symbol.
• Summing per-leg margin to pre-check a defined-risk structure (position grouping makes the real requirement far lower).
• Assignment cleanup in the generic order-event handler reading holdings that aren't updated yet — use OnAssignmentOrderEvent.
• No expiry-slip state cleanup: position-tracking fields never cleared when contracts expire, permanently halting re-entry.
• Pairing route A with per-leg limit prices — factories place market executions; limit pricing needs route B.