Accounts & trading days

A trading account is a persistent, named container with a continuous cash balance that carries day to day. You trade an account one trading day (a session) at a time. Accounts are the foundation of the whole platform — the trading screen, positions, and P&L are all views into a single day under an account.

Accounts and their engines

Every account is created with a fixed engine that decides how it trades:

• Historical — an editable replay ledger. Open any past recorded day, trade it with a clock you control, and the day settles into the carried balance. Because the balance carries forward, editing an earlier day re-threads every later day. Covered in Historical replay.
• Live — paper-trades today's real session against the live tick stream. Past sessions are frozen. Covered in Live trading.
• Broker accounts (Interactive Brokers, Schwab, tastytrade, and others) are coming soon — they appear in the platform but aren't available to trade yet.

Trading is 0DTE SPX-index options only: cash-only, no equities, and no overnight positions, so an account's balance is a single number that simply rolls from one day to the next.

The continuous balance

An account opens with a starting capital. Each trading day opens with whatever cash carried over, you trade, and at the 4:00 PM ET close the day settles — its closing balance becomes the account's new carried balance and the next day picks up from there.

Two numbers describe an account's money:

• Cash balance — the settled carry. It only ever changes when a day settles, so it never reflects an in-progress day's unrealized P&L.
• Current value — the live net-liquidation value while a day is open on the account; otherwise it just equals the cash balance.

Trading days (sessions)

A session is one trading day under an account. Orders, positions, transactions, and the equity curve all live under a session. Each day reports a full financial picture:

• Net liquidation value — opening balance + the day's total P&L.
• Unrealized P&L — mark-to-market gain or loss on open positions.
• Realized P&L — locked-in gain or loss from closed positions and settlements.
• Available buying power and maintenance margin — see Buying power & margin.

A day's status is open, settled, or abandoned. A historical account lands you on its open day (or the latest settled one); a live account has at most one open day — today's.

The clock (historical)

On a historical account, a fresh day starts parked at the open with no clock set. Advancing the clock to a later time fills any pending orders whose conditions were met along the way, marks your positions to that moment, and recomputes financials. Rewinding does the reverse: orders that hadn't yet filled at the earlier time revert to pending, and trades after that time drop out of view.

Crucially, moving time is read-only — it never changes your orders or trades; it just recomputes what the day looks like at the new moment. You can rewind and replay as much as you like. A live account has no clock control: it tracks the real clock.

Per-day history

Whenever you place or cancel an order, the day computes a per-second history of its financials across the whole session and stores it for charting. This is what powers the equity curve on the trading and positions screens.

End of day

When the clock reaches 4:00 PM ET, the day settles automatically: in-the-money options exercise or assign, out-of-the-money options expire worthless, and the results land in realized P&L. The day's closing balance then carries into the account. See End-of-day settlement for the details.