Market replay
Market replay streams recorded market data back through the terminal as if it were live - charts, tape, DOM, and order flow all follow one shared session clock - and lets you trade it against a dedicated replay sim. Pick a symbol and a date range, press play, and rehearse a session as many times as you want.
The pieces
Section titled “The pieces”- The Replay venue - a connection like any other. Point any pane (chart, tape, DOM, blotter…) at it and that pane follows the replay session instead of live data. Replayed charts carry a diagonal REPLAY watermark so a screenshot can never pass as live.
- The Replay Transport widget - the playback deck. One session per terminal: every pane on the Replay venue follows this one deck, wherever it’s docked.
The transport deck
Section titled “The transport deck”- Symbol - picked from the deck’s title bar like any other widget; the venue tab you pick it from selects the replay source (see below).
- Range - start and end (
YYYY-MM-DD HH:MM), entered in your configured display time zone. Leave the end blank to play to the live edge. Set restarts the session at the new start. - Transport - play/pause, ±10s and ±1m jumps, a seek slider, and a speed button cycling 1× → 2× → 5× → 10× → 25× → 50× → 75× → 100×. Sessions start paused.
- Balance - the sim’s starting bankroll. Setting it restarts the sim with a fresh account.
Seeking forward streams the in-between data (your orders and positions survive). Seeking backward restarts the session - the sim resets and panes reload at the new time.
Replay sources
Section titled “Replay sources”Two kinds of source, chosen by which venue you pick the symbol from:
| Source | Data | Fill realism |
|---|---|---|
| Tape-backed (markets Nocterm ingests) | The archived per-print tape + order book | Per-print - limits fill when real prints cross them |
| Candle-synth (client-sourced venues, e.g. Alpaca) | Prints synthesized from 1m history (open → far extreme → near extreme → close) | Bar-replay grade - fills when a bar’s range crosses your price |
Session markets (equities) skip the clock across closed hours while playing, so a replay doesn’t crawl through nights and weekends in silence.
Trading a replay
Section titled “Trading a replay”The Replay venue runs its own sim: market/limit/stop entries, brackets, partial closes, time-in-force, a live equity/PnL readout seeded from the deck’s starting balance. Trading bots can run on the Replay venue too - and when the session restarts (rewind, new range, new balance), running replay bots are stopped with a toast, since the market they were trading just ceased to exist.
Related
Section titled “Related”- Trading bots - running bots against a replay session.
- Time-in-force - fully supported on the replay sim.
- Paper trading - the always-on sim for live markets.