RTH

What it is

RTH stands for Regular Trading Hours — the primary cash-session window for an instrument. For US equity index futures (ES, NQ, YM, RTY and their micro counterparts), RTH typically runs from 9:30am to 4:00pm Eastern Time, matching the cash equity market open and close at the NYSE and Nasdaq. For other asset classes the RTH window differs: crude oil (CL) has its own pit-equivalent session, gold (GC) has a different window again, and so on.

RTH is a contrast term to ETH — Extended Trading Hours — which is the overnight or after-hours session that runs outside the cash window. Most major futures contracts now trade nearly 24 hours a day via CME Globex, so the "session" concept is more about liquidity character and participation profile than literal market open/close.

The exact RTH window for any given instrument is published by its exchange and is editable in Sierra Chart's session settings. Many traders maintain instrument-specific session definitions and apply them consistently across studies, profiles, and statistics.

Why it matters

RTH and ETH have very different liquidity, volatility, and participation characteristics. Inside RTH, real-money institutional flow is most active, spreads are tightest, volume is highest, and price discovery is most efficient. Outside RTH, liquidity thins out, spreads widen, single large orders move price further, and many institutional algos go quiet.

This matters for analysis in several ways:

• Volume profile — an RTH-only profile reflects price acceptance during institutional hours; an ETH-inclusive profile reflects 24-hour acceptance. The shapes can differ substantially, and the POC location can shift.
• Range statistics — measuring "session range" with or without the overnight changes the answer significantly.
• Setup quality — many discretionary traders only consider setups inside RTH because the liquidity environment is more reliable.
• Backtesting — strategies developed on ETH-inclusive data often perform poorly when restricted to RTH (and vice versa) because the regimes are structurally different.

How it appears on Sierra Chart

Sierra Chart treats sessions as first-class objects with editable per-instrument definitions. The chart's session settings define the RTH window, the ETH window, and how the platform should treat them when building bars, computing daily statistics, and rendering profiles. Many studies — including volume profile, daily high/low, and ATR — have an "RTH only" toggle that scopes their computation to the cash session.

For ACSIL developers, the platform exposes session-aware helpers: a study can ask whether a given timestamp falls inside the day session (RTH), the evening session (ETH), or any defined session via IsDateTimeInDaySession, IsDateTimeInEveningSession, and IsDateTimeInSession.

Common patterns / pitfalls

• Define sessions per instrument — ES, CL, GC, and 6E all have different RTH windows. A single global session setting will give wrong answers on at least one.
• Daylight saving handling — RTH is published in exchange local time (typically Eastern for CME equity products), so the wall-clock window shifts during DST changeovers. Sierra Chart handles this if the chart timezone is set correctly.
• Don't mix definitions across studies — if your volume profile is RTH-only but your ATR is full-session, comparing them across instruments will mislead.
• Bar timing on session boundaries — bars that straddle the RTH open or close can be partial. Most studies handle this implicitly but the edges deserve a sanity check.
• Range charts and ETH — Range bars on ETH-inclusive charts can span the RTH→ETH gap and produce misleading bar opens; this is a well-known ACSIL trap that requires deliberate session filtering.

Related SCS studies

SCS does not currently ship an RTH-specific study, but every SCS analytical study that depends on session boundaries — Session ATR Percent is the clearest example — exposes session-time inputs so traders can choose between RTH and ETH framings.