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Relative Volume by Time of Day

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Trading volume is not spread evenly across the session — it typically surges near the open, thins out at midday, and builds again into the close. Time-adjusted RVOL corrects for that pattern by comparing current cumulative volume against the historical average at the same point in the trading day, rather than against a completed full-day average.

See why volume changes Relative volume guide

Educational-use notice

Time-adjusted RVOL is an estimate based on historical patterns. News, halts, auctions, market-wide events, corporate actions, and changing liquidity can make the current session differ materially from the baseline. This guide provides general market education and does not recommend buying, selling, shorting, or holding any security.

Relative Volume by Time of Day

Relative volume must account for the market’s intraday volume pattern. Stocks do not normally trade at a constant rate from the opening bell to the close.

Volume often follows a U-shaped pattern:

That pattern means 500,000 shares at 9:45 a.m. can be ordinary for one stock and extraordinary for another. It also means comparing partial-day volume with average completed daily volume can materially understate early activity.

The preferred intraday formula is:

Time-Adjusted RVOL =
Current Cumulative Volume by Time T
÷
Average Historical Cumulative Volume by Time T

Direct answer: Time-adjusted RVOL compares the current session with historical sessions at the same point in the trading day. It is generally more useful intraday than dividing current volume by average full-day volume.

Why Stock Volume Changes Throughout the Day

Volume changes because market participation and information flow are not evenly distributed.

Near the Open

The market processes:

Midday

Activity may slow because:

Near the Close

Volume may rise because of:

The exact curve varies by stock, sector, catalyst, day of week, and market regime.

A Typical Intraday Volume Curve

Hypothetical example — for education only.

A hypothetical stock with average daily volume of 2 million shares may show:

Time Average cumulative volume Share of normal day
9:35 a.m.120,0006%
10:00 a.m.400,00020%
10:30 a.m.650,00032.5%
11:00 a.m.800,00040%
Noon1,000,00050%
1:00 p.m.1,150,00057.5%
2:00 p.m.1,350,00067.5%
3:00 p.m.1,550,00077.5%
3:30 p.m.1,700,00085%
4:00 p.m.2,000,000100%

The stock completes half its normal daily volume by noon, not at the chronological midpoint of the session.

Full-Day RVOL versus Time-Adjusted RVOL

Hypothetical example — for education only.

Assume at 10:00 a.m.:

Current cumulative volume: 800,000
Average daily volume: 4,000,000
Average volume by 10:00 a.m.: 400,000

Full-day RVOL:

800,000 ÷ 4,000,000 = 0.20

Time-adjusted RVOL:

800,000 ÷ 400,000 = 2.0

The stock has completed only 20% of a normal full day, but it is trading at twice its normal 10:00 a.m. pace.

During the trading session, the second reading is generally more informative.

Relative Volume at the Market Open

The opening period is naturally active.

A high-quality same-time baseline must include the normal opening surge.

Example

Hypothetical example — for education only.

Historical average by 9:45 a.m.:

200,000 shares

Current volume by 9:45 a.m.:

600,000 shares
Time-adjusted RVOL = 600,000 ÷ 200,000 = 3.0

The stock is trading at three times its normal opening pace.

Opening-Specific Factors

A large opening print should be identified separately so users know whether RVOL reflects an auction or continuous trading.

Relative Volume During the First Hour

The first hour often determines:

A stock with 4 premarket RVOL may open and decline toward 1.5 regular-session RVOL if interest disappears.

Another may begin at 2 premarket RVOL and accelerate to 5 after the open.

Useful first-hour metrics:

Midday Relative Volume

Midday volume is normally lower.

A five-minute volume burst at noon can be meaningful even when the daily cumulative RVOL changes only slightly.

Example

Hypothetical example — for education only.

Current noon cumulative volume:

2,000,000 shares

Average noon cumulative volume:

1,000,000 shares
Time-adjusted RVOL = 2.0

Current five-minute bar:

200,000 shares

Average comparable noon bar:

25,000 shares
Bar RVOL = 8.0

The stock has sustained twice-normal daily pace and is experiencing a fresh eight-times-normal midday burst.

Possible causes:

The bar should be investigated rather than interpreted automatically.

Why Midday RVOL Can Be Misleading

A low-volume stock may show an extreme midday bar because the normal denominator is tiny.

Hypothetical example — for education only.

Example:

Average noon five-minute volume: 500 shares
Current noon bar: 10,000 shares
Bar RVOL = 20

At a $1 share price:

Dollar volume = $10,000

The ratio is extreme, but the bar may still be practically untradable.

Always pair midday bar RVOL with:

Relative Volume During the Final Hour

The final hour often sees increasing participation.

A stock that maintains elevated RVOL into the close may show:

Useful metrics:

Closing-Auction Effects

A closing auction can add a large block of volume at 4:00 p.m.

Hypothetical example — for education only.

Suppose:

Continuous-session volume before close: 5,000,000
Closing-auction volume: 3,000,000
Final daily volume: 8,000,000
Average daily volume: 4,000,000

Pre-auction RVOL:

5,000,000 ÷ 4,000,000 = 1.25

Final RVOL:

8,000,000 ÷ 4,000,000 = 2.0

The completed day shows 2 RVOL, but 37.5% of total volume came from one closing event:

3,000,000 ÷ 8,000,000 = 37.5%

A well-designed scanner should display auction contribution separately.

Projected Volume by Time of Day

Projected volume uses the historical completion percentage.

Projected Daily Volume =
Current Cumulative Volume
÷
Historical Completion Percentage

Example at 11:00 A.M.

Hypothetical example — for education only.

Current volume:

1,600,000

Normal completion percentage:

40%

Projected volume:

1,600,000 ÷ 0.40 = 4,000,000

Average daily volume:

2,000,000

Projected RVOL:

4,000,000 ÷ 2,000,000 = 2.0

The projection assumes the current normalized pace persists.

It can change rapidly after news, halts, or afternoon acceleration.

RVOL Acceleration by Time

A stock may become more or less abnormal as the day progresses.

Hypothetical example — for education only.

Example:

Time Time-adjusted RVOL
10:00 a.m.1.5
10:30 a.m.2.0
11:00 a.m.2.6
Noon3.1

The normalized pace is accelerating.

Hypothetical example — for education only.

Percentage acceleration from 10:00 to noon:

(3.1 − 1.5) ÷ 1.5 × 100 = 106.7%

Interpret with price:

Each may signal momentum, liquidation, or absorption.

Decelerating RVOL

Hypothetical example — for education only.

Example:

Time RVOL
9:45 a.m.6.0
10:30 a.m.4.0
Noon2.5
2:00 p.m.1.8

The stock remains above normal, but abnormality is fading.

Possible explanations:

A decline from 6 to 2.5 does not mean volume is weak. It remains 2.5 times normal.

Stable High RVOL

Hypothetical example — for education only.

Example:

10:00 a.m.: 3.1
11:00 a.m.: 3.0
Noon: 3.2
2:00 p.m.: 3.1

The stock is sustaining approximately three times normal activity.

Persistent high RVOL can be stronger evidence of a structural change than an opening spike that collapses immediately.

Useful persistence fields:

Premarket-to-Regular-Session Transition

Premarket and regular-session RVOL use separate baselines.

At 9:30 a.m.:

Hypothetical example — for education only.

Example:

Premarket RVOL: 8
Regular-session RVOL at 10:00 a.m.: 3

Interpretation:

Hypothetical example — for education only.

Another example:

Premarket RVOL: 2
Regular-session RVOL: 6

Participation accelerated after the open.

Day-of-Week Effects

Volume patterns can vary by day.

Possible tendencies:

A sophisticated baseline can compare the current session with:

A platform should begin with a broad baseline and offer weekday-specific context as a secondary measure.

Event-Day Volume Curves

Earnings days can have a different curve from ordinary sessions.

A stock may complete:

Using an ordinary-day curve may misproject the final total.

Potential event-specific curves:

Display event-specific projections as estimates with lower confidence until enough comparable events exist.

Market-Wide Time-of-Day Effects

Macro events can reshape the curve.

Examples:

A stock’s RVOL may surge because the entire market becomes active.

Market-adjusted RVOL:

Stock RVOL ÷ Broad-Market RVOL

Sector-adjusted RVOL:

Stock RVOL ÷ Sector Median RVOL

These help distinguish company-specific abnormality from broad participation.

Time-Zone and Exchange-Calendar Handling

Production systems must use:

Do not use a fixed UTC bucket without mapping it to the exchange’s local session.

A 9:30 a.m. Eastern open changes UTC offset when daylight-saving time changes.

Half-Day Sessions

A shortened session should not use an ordinary full-day curve.

Possible approach:

Do not assume a half-day is simply a normal day compressed proportionally. Holiday participation can be structurally different.

Trading Halts

During a halt:

The platform should:

A stock halted for 45 minutes cannot be projected reliably from an ordinary time curve.

Building a Time-of-Day RVOL Baseline

Step 1: Gather Historical Intraday Bars

Use one-minute or five-minute bars.

Step 2: Separate Sessions

Step 3: Calculate Cumulative Volume

For each historical day and time bucket.

Step 4: Calculate Mean and Median Curves

Store:

Step 5: Compare the Current Session

Calculate:

Step 6: Apply Confidence Rules

Reduce confidence for:

Complete Example

Hypothetical example — for education only.

Assume:

Average daily volume: 3,000,000
Average volume by 10:30 a.m.: 900,000
Average volume by noon: 1,500,000
Average volume by 3:00 p.m.: 2,300,000

Current session:

10:30 a.m.: 1,800,000
Noon: 2,700,000
3:00 p.m.: 3,450,000

RVOL:

10:30 a.m.: 1,800,000 ÷ 900,000 = 2.0
Noon: 2,700,000 ÷ 1,500,000 = 1.8
3:00 p.m.: 3,450,000 ÷ 2,300,000 = 1.5

The stock remains active, but normalized participation is decelerating.

Possible interpretation:

Dashboard Display Requirements

Display:

Chart

Plot:

This makes the calculation auditable.

Related Guides

Frequently Asked Questions

Why is stock volume higher at the open and close?

The open processes overnight information and accumulated orders. The close attracts institutional, benchmark, index, and market-on-close activity.

What is time-adjusted RVOL?

It compares current cumulative volume with average cumulative volume at the same time during prior sessions.

Why is full-day RVOL misleading in the morning?

The current day is incomplete while the denominator represents a completed day.

What is a normal volume curve?

Many stocks show high activity near the open, lower midday activity, and increasing volume near the close.

Can RVOL decline while volume remains high?

Yes. The stock may remain above normal while the pace becomes less abnormal.

What is bar RVOL?

It compares the current chart bar’s volume with historical comparable bars.

Why should auctions be separated?

One large opening or closing print can dominate total volume without representing sustained continuous trading.

How are halts handled?

Projections should be qualified or paused because the ordinary time curve no longer applies.

Should half-days use a normal baseline?

No. Use separate shortened-session baselines or exclude them.

Does premarket RVOL continue after 9:30 a.m.?

Preserve it as context, but calculate regular-session RVOL using a separate baseline.