Settlement cycles

Definition

Settlement is when a trade’s cash and securities actually change hands, as distinct from when the trade executes. US equities and ETFs settle one business day after the trade (T+1) under the SEC’s 2023 rule amendment (effective May 2024); listed options premium also settles T+1; futures have no deferred settlement of the position at all — they mark to market in cash daily.

How it works / structure

• Equities/ETFs (T+1): buyer’s cash and seller’s shares are exchanged the next business day through the clearing system; sale proceeds exist as buying power immediately at most brokers but as settled cash only at T+1.
• Options: premium settles T+1; exercise/assignment stock deliveries settle on the equity cycle from the exercise date.
• Futures: positions are marked to market every day — variation margin moves in cash daily (per CME’s education materials), so “settlement” is continuous rather than deferred; final settlement at expiry is physical delivery or cash per contract spec.
• Simulation parameters: cash-availability timing for equity sales (T+1), option premium timing (T+1), daily futures cash flows; cash-account rules (acct-settlement) constrain strategies that recycle capital quickly.

When it applies

Any strategy that reuses proceeds quickly (high-turnover equity strategies in cash accounts), any position ending in delivery (assignments, physical futures), and any margin computation — margin and settlement interact through buying-power rules (acct-margin-rules).

Risk profile & failure modes

• Good-faith violations: in cash accounts, buying with unsettled proceeds and selling before settlement violates Regulation T practice (acct-settlement details the violation ladder).
• Delivery fails: a seller who cannot deliver by settlement creates a fail; regulatory close-out rules then force resolution.
• Futures cash drains: daily variation margin means an adverse week drains account cash daily — a position can be “right eventually” and still exhaust cash before eventually arrives.
• Cycle mismatches: exercising options into stock spans two settlement regimes; the interim exposure is real.

Evidence & limits

Settlement cycles are regulation (SEC T+1 final rule; CME daily settlement rules), not hypotheses. The T+1 regime dates from May 2024; historical analyses spanning earlier periods must account for T+2 (2017-2024) and T+3 (before 2017) conventions.

Falsifiable-thesis examples

Illustrations only, not signals:

• “A simulated cash-account strategy with same-week re-entry will show no good-faith violations under T+1 timing” — falsified by any violation flagged in replay.
• “US equity settlement will remain T+1 through the strategy’s 12-month evaluation window” — falsified by a further SEC cycle change taking effect in the window.

Cross-references

• Account rules: acct-settlement, acct-margin-rules
• Options interactions: ms-expiration-exercise-assignment
• Futures cash mechanics: ms-futures-margin
• Friction modeling: ms-slippage-friction