importance of closing volume

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Lung Closing Volume

and (4) the closing lung volume of a neonate overlaps with the tidal volume (i.e., airway closure occurs at the end of expiration).

From: A Practice of Anesthesia for Infants and Children (Fourth Edition) , 2009

Related terms:

Lung Mechanics in Disease

Claude Guérin , ... Edgardo D'Angelo , in Mechanical Ventilation , 2008

Closing Volume

Assessment of the closing volume (CV) was originally performed by inhaling a bolus of xenon-133 at the onset of an inspiratory vital capacity maneuver: during the subsequent expiration, the concentration of the tracer suddenly increased, reflecting the onset of airway closure at the bottom of the lungs. 9 The volume at which this occurs is termed CV. Small airway closure is a common phenomenon in stable patients with COPD. 10 Behind closed airways there is gas trapping, so that, with the progression of peripheral airway disease, CV becomes larger than FRC, 10 with consequent maldistribution of ventilation and impaired gas exchange.

In relaxed, mechanically ventilated patients with AVF, the CV has been indirectly assessed by constructing the quasistatic inflation volume-pressure (V-P) curve of the respiratory system ( Fig. 10.3 ): this curve exhibits an inflection point at low lung volumes that reflects the critical opening pressure (Po) and volume (Vo), which are the pressure and volume, respectively, at which previously closed small airways reopen. 11 In seven patients with COPD, Vo was greater than the end-expiratory lung volume on ZEEP, a finding indicating that some peripheral airways were probably closed throughout the breathing cycle, whereas others cyclically opened and closed. In contrast, in three patients with COPD, Vo was lower than the end-expiratory lung volume on ZEEP, a finding indicating an absence of peripheral airway closure during baseline ventilation. Other implications of these findings are discussed later.

Ventilation, Blood Flow, and Gas Exchange

Frank L. Powell PhD , ... John B. West MD, PhD, DSc , in Murray and Nadel's Textbook of Respiratory Medicine (Sixth Edition) , 2016

Reaction Rates with Hemoglobin

When oxygen (or carbon monoxide) is added to blood, its combination with hemoglobin is quite fast, being close to completion in 0.2 second. Such reaction rates can be measured using special equipment in which reduced hemoglobin and dissolved oxygen are rapidly mixed and the rate of formation of oxyhemoglobin is measured photometrically. Although hemoglobin is oxygenated rapidly within the pulmonary capillary, even this rapid reaction significantly delays the loading of oxygen by the red cell.

The transfer of oxygen from the alveolar gas to its combination with hemoglobin in the red cell can therefore be regarded in two stages: (1) diffusion of oxygen through the blood-gas barrier, including the plasma and red cell interior; and (2) reaction of the oxygen with hemoglobin ( Fig. 4-19A ). Although at first sight these two processes are very different, it is possible to treat them mathematically in a similar way and to regard each as contributing its own “resistance” to the transfer of oxygen. Such an analysis was carried out by Roughton and Forster, 86 who showed that the following relationship exists:

where D l refers to the diffusing capacity of the lung, D m is the diffusing capacity of the membrane (which includes the plasma and red cell interior), θ is the rate of reaction of oxygen (or carbon monoxide) with hemoglobin (expressed per milliliter of blood), and V c is the volume of blood in the pulmonary capillaries.

In the normal lung the resistances offered by the membrane and blood reaction components are approximately equal. This means that, if the capillary blood volume is reduced by disease, the measured diffusing capacity of the lung is lowered. In fact, the equation can be used to separate the two components. To do this, the diffusing capacity is measured at both high and normal alveolar P o 2 values. Increasing the alveolar P o 2 reduces the value of θ for carbon monoxide because the carbon monoxide has to compete with a high pressure of oxygen for the hemoglobin. If the resulting measurements of 1/D l are plotted against 1/θ, as shown in Figure 4-19B , the slope of the line is 1/V c , whereas the intercept on the vertical axis is 1/D m .

Lung function testing

Roger Hainsworth , in Foundations of Anesthesia (Second Edition) , 2006

ANATOMIC DEAD SPACE AND CLOSING VOLUME

Anatomic dead space is defined as the volume of the conducting airways, where no gas exchange takes place ( Fig. 50.7 ). Closing volume is the volume towards the end of a forced expiration, after which some airways have effectively closed and more of the expired gas comes more from the relatively poorly ventilated regions of the lung. Closing capacity is the volume of gas within the lungs at the point at which airways closure begins. It is the sum of closing volume and residual volume.

These values can be determined using the technique described by Fowler, which involves a single breath of pure oxygen. The method requires a rapidly responding nitrogen meter, a recording spirometer, and an X–Y plotter to relate the expired nitrogen concentration to the expired volume. The procedure is for the subject to make a maximal exhalation to atmosphere, then take a vital capacity inspiration of 100% oxygen. The subject then exhales to residual volume into the spirometer, during which continuous recordings of nitrogen concentration and volume are made. Initially, the expired gas comes from the dead space and is nitrogen free. There is then a mixing phase; anatomic dead space is determined by bisecting the line of mixing. As the breath continues, alveolar gas is expired; if ventilation is even, the plateau rises only slowly. A steeper rise during the plateau phase can be used as a measure of uneven ventilation. Towards the end of the exhalation the nitrogen concentration may show a secondary rise. This is because the airways in the more compliant regions of the lung (bases) have closed and the exhalate comes from the apical part, which, because of its lower compliance, received less oxygen during the initial inspiration. The volume expired after the start of this secondary increase in nitrogen is the closing volume. It is small in young healthy subjects but increases with age, and is particularly large in the presence of obstructive lung disease.

Pulmonary considerations in the older patient

Meryl Cohen , in A Comprehensive Guide to Geriatric Rehabilitation (Third Edition) , 2014

↑ Residual volume (RV)

↑ Functional residual capacity (FRC)

↓ or ↔ Total lung capacity (TLC)

↑ Closing volume

↓ Maximal voluntary ventilation (MVV); ↓ 30% between 30 and 70 years of age

↓ Vital capacity (VC); ↓ 25% between 30 and 70 years of age

↓ Forced expiratory volume (FEV 1 )

↓ Arterial pressure of oxygen ( Pa O 2 ); 75 mmHg is normal for 70 years of age

↓ Oxygen saturation

↓ Diffusing capacity of carbon monoxide (DLCO)

Mechanical Ventilation and Respiratory Care

Shekhar T. Venkataraman , in Pediatric Critical Care (Fourth Edition) , 2011

Parenchymal Lung Disease

ARDS, idiopathic respiratory distress syndrome, and interstitial pneumonias are examples of parenchymal lung disorders that are characterized by a reduction in FRC, an increase in closing volume higher than FRC, and diffuse subsegmental atelectasis. These diseases are characterized primarily by inadequate oxygenation because of V/Q mismatching and intrapulmonary shunting. Therapy should be directed toward maintaining lung volumes higher than closing volume throughout the respiratory cycle, increasing FRC higher than closing volume, and reducing V/Q mismatching and intrapulmonary shunting. The most effective method of achieving these goals is with an increase of mean lung volume, which is usually obtained with an increase of the mean airway pressure. During spontaneous breathing without any ventilatory assistance, CPAP is the most reliable method to increase lung volume. CPAP is effective in improving oxygenation in idiopathic respiratory distress syndrome 14 and ARDS. 84,85 During positive-pressure breathing, the level of PEEP required to maintain adequate oxygenation primarily depends on the severity of the underlying lung disease. The degree of intrapulmonary shunting, ventilation-perfusion mismatching, alveolar edema, alveolar collapse, and decreased compliance is directly proportional to the severity of lung disease. As the severity of lung disease increases, the airway pressures required to maintain adequate gas exchange also increase. Therefore arbitrary limits cannot be placed on the level of PEEP or mean airway pressure that will be necessary to maintain adequate gas exchange. Tidal volumes should be limited to 6 to 8 mL/kg. Studies in adults, including the ARDSNetwork study, have demonstrated that using high tidal volumes of 12 ml/kg is detrimental to patient outcome. 86,87 When high levels of PEEP are used, PIP may reach levels that contribute to pulmonary air leak and barotrauma. Attempts to decrease PIP with the reduction of tidal volume will result in decreased mean airway pressure, mean lung volume, and decreased minute ventilation. With a high airway pressure maintained throughout inspiration, pressure-control ventilation may provide higher mean airway pressure and maintain a higher mean lung volume compared with volume-control ventilation. A general rule of thumb is to consider switching to pressure-limited time-cycled ventilation when PEEP requirement is more than 10 cm H 2 O. For hyperinflation to be avoided, the end-inspiratory pause pressure should not exceed 35 cm H 2 O. Hypercapnia may be permitted under these circumstances provided arterial pH is adequate (permissive hypercapnia). It has been recommended that the optimal PEEP should be set above the critical closing or critical opening pressure of the airways. This can be deduced by the lower inflection point generated with static pressure-volume loops ( Figure 49-19 ). As the lung is inflated from zero end-expiratory pressure, in many lungs there is an abrupt change in compliance as denoted by the “lower inflection point.” It is generally thought that this is the critical opening pressure of the airways above which the alveoli and airways remain open. As the lung is further inflated in increments, the pressure-volume slope increases and then abruptly changes direction as noted in Figure 49-19 as the “upper inflection point.” It is generally thought that the upper inflection point reflects overdistension of the alveoli. The general recommendation is to keep the PEEP level above the lower inflection point and to keep the end-inspiratory pause pressure below the upper inflection point. Currently, bedside use of static pressure-volume loops to set PEEP is not a standard practice in infants and children. Therefore the level of PEEP should be set by titrating the level of PEEP and selecting the level by the maximal level of improvement in oxygenation compliance seen without affecting systemic hemodynamics. The repeated collapse and reopening of the lung units at low lung volume have been shown to contribute to ventilation-induced lung injury. 88-91 A strategy combining recruitment maneuvers, low-tidal volume, and higher PEEP has been shown to decrease the incidence of barotrauma or volutrauma. 88-91

Pulmonary Edema

Hugh O'Brodovich MD , in Kendig's Disorders of the Respiratory Tract in Children (Ninth Edition) , 2019

Pulmonary Function Tests

Initially, vascular engorgement may lead to an increase in the diffusing capacity (D l CO) by increasing the amount of perfused vasculature within the gas exchanging regions of the lung. As interstitial edema increases, there will be an increase in closing volume, a decrease in maximum expiratory flow, an increase in V/Q inhomogeneity, and a decrease in arterial P o 2 . With alveolar flooding, there is further air trapping, increased vascular resistance, decreased lung volumes, decreased dynamic lung compliance, decreased D l CO, and progressive hypoxemia arising from the increased intrapulmonary right-to-left shunting and rising Pa co 2 , the latter further decreasing alveolar PO 2 . In patients with a patent foramen ovale, right-to-left shunting at the atrial level may occur as a result of the associated pulmonary hypertension and concomitant increase in right ventricular end diastolic and right atrial pressures.

Anaesthetic Issues During Labour

Alistair Milne , Alistair Lee , in Obesity , 2013

Oxygenation

In both pregnancy and obesity, the diaphragm is pushed in a cephalad direction. This leads to a reduction in functional residual capacity, the lung volume at the end of a normal expiration. Individuals of normal weight experience closure of small airways, the closing volume, at a lung volume significantly below their functional residual capacity. In obese individuals, the functional residual capacity is reduced to an extent that it is smaller than the closing volume. As a consequence, obese individuals experience small airway closure while breathing normally. This is associated with ventilation perfusion mismatch leading to reduced oxygen saturation [14] . Oxygen consumption is significantly greater in obesity and pregnancy. In combination, these factors mean that even with good pre-oxygenation the time to critical desaturation is reduced. Desaturation to a critical level (defined as <90% saturation, the critical inflection point) occurs in less than 3 min in the obese patient compared to longer than 6 min in a normal individual [15] . This decrease is more rapid in the obstetric population. A head up tilt during pre-oxygenation increases the time to critical desaturation by about 1 min. This is due to gravity causing an increase in functional residual capacity by allowing the abdominal contents, fat pannus and diaphragm to move caudally.

During the immediate post-operative period, there is a significant risk of hypoxaemia after general anaesthesia in the obese patient. The lung volume may be reduced even allowing for delivery. Once the patient has been extubated, the lungs will no longer contain 100% oxygen as a reserve, unless the patient is breathing very effectively through a completely sealed face mask, and the time to critical oxygen desaturation can be very short. The use of volatile agents significantly depresses respiratory drive from hypercapnia, and the response to hypoxaemia is negligible until the gases are cleared. As a consequence, airway obstruction can quickly lead to death.

Pulmonary Function Testing

Bruce H. Culver , in Clinical Respiratory Medicine (Fourth Edition) , 2012

Tests of Gas Distribution

Abnormalities of spirometry and airflow rate reflect overall narrowing of airways, but most lung diseases affect airways heterogeneously, which leads to abnormalities of gas distribution that may be more sensitive indicators of early airway disease.

As lung volume decreases, the smaller, intraparenchymal airways decrease in caliber until they close at low lung volume and ventilation to or from alveoli beyond them ceases. Because there is a vertical gradient in the pleural pressure that surrounds the lungs, the lung tissue is less distended in dependent regions than at higher levels in the thorax. In late exhalation, dependent airways close (i.e., these areas reach their regional RV), whereas air continues to flow from the upper portions of the lung until they too close, and overall RV is reached. The beginning of this wave of ascending airway closure can be detected by physiologic tests and is termed closing volume. Closing volume usually is expressed as a percentage of VC. That is, a closing volume of 20% means that airway closure can be detected during a slow exhalation when 20% of the VC remains before RV is attained ( Figure 9-7 ). Alternatively, when RV is measured, this can be added to closing volume, and the sum, termed closing capacity, is expressed as a percentage of TLC.

Both of these measures have been used as tests of early airway dysfunction in the natural history of COPD. Abnormalities can be detected in a high percentage of smokers, but the prognostic usefulness is limited, because this group includes many who do not go on to develop progressive airflow limitation. On an individual patient basis, the closing volume is most helpful in its relationship to the lung volume at which tidal breathing occurs. When airway closure occurs at a volume below FRC, the airways are open throughout the lungs during tidal breathing, but when airway closure occurs above FRC, the affected alveoli are underventilated. Because the dependent regions are well perfused, premature airway closure creates a low ventilation-perfusion region, which contributes to hypoxemia. This abnormality occurs when the closing volume is increased by normal aging or COPD, and by the effect of peribronchial edema in left ventricular failure. Similar consequences are observed when FRC is reduced by recumbent posture or by obesity.

Respiratory Physiology in Infants and Children

Etsuro K. Motoyama , Jonathan D. Finder , in Smith's Anesthesia for Infants and Children (Eighth Edition) , 2011

Closing Volume and Closing Capacity

Beside the lungs and chest wall, the air passages themselves have a compliance that may be important. With deep inspiration, the airway caliber increases in size (interdependent of airways and lung volume), whereas the airway caliber decreases during passive expiration, with an even bigger increase during forced expiration with dynamic compression. Closing volume (CV) is the lung volume above RV at which air flow during expiration ceases from dependent lung zones (i.e., lower lung segments in the upright position), presumably because of the closure or collapse of small airways. Closing capacity (CC) is the sum of CV above RV plus RV.

Whether this closure is anatomic or merely the result of dynamic compression and reduction in flow (see Dynamic Properties ) is controversial ( Hughes et al., 1970; Hyatt et al., 1973 ). Because the patency of small airways depends in part on the elastic recoil of the lungs, CC as a percentage of TLC is relatively high in young children and would be even higher, at least theoretically, in infants ( Mansell et al., 1972 ). CC increases with aging as well as with small airway disease, such as chronic bronchitis caused by smoking and emphysema in adults.

Lung compliance is reduced in most situations in which lung volume is decreased (e.g., the removal of lung tissue, atelectasis, and intrapulmonary tumors), although it is normal when corrected for lung volumes. Compliance is also decreased when surface forces are increased, as it is in IRDS with increased surface force (or decreased surfactant), or when elastic recoil is abnormally increased (e.g., in interstitial pulmonary fibrosis).

Emphysema is associated with a loss of elastic recoil and therefore an abnormal increase in compliance. Chest-wall compliance decreases with conditions such as scleroderma, kyphoscoliosis, and ankylosing spondylitis involving the thoracic structures.

Intubation, Rescue Devices, and Airway Adjuncts

Aaron J. Donoghue MD, MSCE , Ron M. Walls MD , in Pediatric Emergency Medicine , 2008

RESPIRATORY MECHANICS

The pediatric thoracic skeleton is largely cartilaginous and much more compliant than the adult skeleton. Elastic recoil of the chest wall in the young child is essentially absent. A given change in thoracic pressure will result in a larger change in lung volume, similar to the physiology seen in an adult with emphysema. A given change in volume is associated with little or no change in pressure, so that a greater amount of work is required to generate a tidal breath.

The high compliance of the pediatric chest wall results in a closing volume (CV) (volume at which terminal bronchioles collapse because they are no longer supported by elastic recoil) that can be elevated with respect to functional residual capacity (FRC). If the already diminished elastic recoil is impaired (e.g., by supine positioning), CV can exceed FRC to an even greater extent, resulting in the absence of ventilation of some lung segments during normal tidal breathing. Young patients therefore have a greater tendency for intrapulmonary shunting and hypoxemia with the positioning required for airway management.

Accessory respiratory muscles in young children are composed of a lower percentage of slow-twitch muscle fibers and are more susceptible to fatigue compared to the diaphragm. Also, the architecture of the pediatric thorax (horizontal rib orientation with extensive cartilage composition) is such that intercostal and suprasternal muscles are poorly recruited to assist in respiratory effort.

Cboe Global Markets

The Impact Closing Auctions Have on Volumes

When we notice a new trading trend, we look for ways that we can improve our exchanges to better fit the way our customers use them. As closing auctions become an increasingly important part of the trading day, we wanted to uncover ways to enhance end-of-the-day trading for market participants. In our latest analysis, we explore how closing auction events impact volumes, and share how upcoming changes to the close on Cboe’s BZX exchange may benefit participants.

Closing Time

The opening and closing prints typically make up the largest individual trades for the day, and trading near the close has steadily gained more popularity over time. In October the closing auction made up about 4.5% of total market volume, as seen in Figure 1 below. But how do closing auction events impact these volumes?

Figure 1 Auction Percentage of Total Volume 1

Closing Auction Events by Exchange

To prepare for the closing auctions, listing exchanges follow a specific timeline of events leading up to the auction print. Here’s a guide to closing auction events and the times at which these events occur across the listing markets.

Figure 2 Closing Auction Key Events

Each event has its own significance, which is reflected in the volume curves for each market. In order to analyze trading volumes going into the close, we studied the most liquid securities on each listing venue. For Nasdaq and NYSE, we looked at all S&P 500 single stock names that are either NYSE or Nasdaq listed securities, respectively. For Cboe BZX and NYSE Arca, we calculated a 21-day moving average of total volume to find the top 10 most liquid ETFs on each exchange.

Volume Trends Near the Close

Figure 3 depicts the percent of total volume from 3:30 p.m. to 4 p.m. on each listing exchange and shows there are significant upticks in volume during the closing auction events on each exchange. The events listed in Figure 2 above, drive the percentage of total volume for all listing exchanges to increase up until the final seconds of the trading day. During that time, each exchange experiences a spike in volume almost five times greater than continuous trading volumes throughout the rest of the regular trading session.

Figure 3 Percentage of Total Volume by Minute 5

Transaction Rate Near the Close

In addition to studying closing volume trends, we found it important to analyze a transaction rate calculated as the amount of transactions per second on each listing exchange. We took a simple average of total transactions on each exchange over the same 21-day trading period used before. As you can see in Figure 4, we found the increase in transactions per second around key closing auction events was similar to the increase in total volume. At 3:50pm, there is a 50–75% increase in transactions per second. The transaction rate continues to steadily increase until the final minutes of the day. When exchanges stop accepting orders and allowing order cancels, the transaction rate returns to the same elevated levels and the closing auction begins.

Figure 4 Transaction Rate Per Second 6

Spreads Near the Close

Our findings emphasize the importance of the closing auction and the continuous session period right before the auction. Although auctions are considered outsized trading events, we found that there is typically a large amount of liquidity available near the close during the continuous session. The transaction rate spikes seen at the end of the day are also associated with the narrowest quoted spreads of the day, as shown in Figure 5 below. To determine this, we took the average basis point spread by minute for all names in the S&P 500. Spreads throughout the day are downward sloping and are typically widest at the open, as they continue to decrease until the close. However, there is usually a small increase in spreads at 3:50 p.m., when an important closing auction event occurs.

Figure 5 S&P 500 Average Spreads per Minute 7

In this type of environment, trading flexibility is key, which is why Cboe plans to propose changes to the BZX close time cutoffs to allow participants to benefit from the higher volume and added information seen pre-close. By doing so, participants may also benefit from the increased liquidity environment, without having to commit quantity to the closing print.

Contact your Cboe Global Markets coverage team to learn more about how these changes may help you enhance your execution.

Footnotes 1, 5, 6, 7 Source: Cboe Market Data

Footnote 2 Source: Nasdaq

Footnote 3 Source: NYSE

Footnote 4 Source: NYSE Arca

Footnote 8 Source: Cboe

The information in this letter is provided for general education and information purposes only. No statement(s) within this letter should be construed as a recommendation to buy or sell a security or to provide investment advice. Supporting documentation for any claims, comparisons, statistics or other technical data in this letter is available by contacting Cboe Global Markets at www.cboe.com/Contact .

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Technical Analysis

Technical Analysis Basic Education

Using Trading Volume to Understand Investment Activity

Investors analyze trading volume when deciding whether to buy or sell a security

Trading volume is the total number of shares of a security that were traded during a given period of time. Trading volume is a technical indicator because it represents the overall activity of a security or a market. Investors often use trading volume to confirm the existence or continuation of a trend , or a trend reversal. Essentially, trading volume can legitimize a security's price action , which can then aid an investor in their decision to either buy or sell that security.

Key Takeaways

Trading Volume and Momentum

Trading volume can help an investor identify momentum in a security and confirm a trend. If trading volume increases, prices generally move in the same direction. That is, if a security is continuing higher in an uptrend, the volume of the security should also increase and vice versa.

For example, suppose company ABC's stock increased in price by 10% over the past month. An investor is interested in the company and wants to purchase 1,000 shares. They conduct a fundamental analysis of the company and see that its earnings and revenues have consistently increased over the past year. However, the investor is not confident the stock will continue in this uptrend and is worried that the trend may reverse.

In this example, trading volume analysis can be very useful. The investor sees that there was a steady increase in ABC's trading volume over the past month. They also notice that the trading volume was the highest that ABC stock had experienced over the past two years, and that the stock is continuing to trend higher. This signals to the investor that ABC is gaining momentum and gives them confidence that the trend should continue higher. Thus, the increase in trading volume led the investor to purchase 1,000 shares of ABC stock.

Trading Volume and Price Reversals

Trading volume can also signal when an investor should take profits and sell a security due to low activity. If there is no relationship between the trading volume and the price of a security, this signals weakness in the current trend and a possible reversal .

For example, suppose company ABC extended its uptrend for another five months and increased by 70% in six months. The investor sees that share prices of company ABC are still in an uptrend and continues to hold on to the shares. However, the trading volume is decreasing. This could signal to the investor that the bullish uptrend in ABC stock is beginning to lose momentum and may soon end.

The following week, the share price of ABC stock decreases by 10% in one trading session after being in an uptrend for six months. This results in the stock breaking its upward trend. More significantly, the trading volume spikes higher when compared to its average daily trading volume (ADTV) . The investor sells out of all the shares of ABC the next day because the combination of a sharp drop in price and spike in trading volume confirmed that the uptrend might be coming to an end and a reversal might be in the offing.

Use Volume For More Trading Insight

What Is a Good Trading Volume?

Good trading volume for a security is hard to define because trading volume's value comes into play when looked at in context with other indicators, such as price direction and volatility. Any level of volume that provides investors with specific insight into a security's price action (and a sense of the trading interest in that security) can be thought of as a good trading volume.

What Does High Trading Volume Mean?

High trading volume (relative to past measures of that volume) that accompanies rising prices or an upward trend can signal strong interest in a security by buyers. On the other hand, high trading volume that accompanies dropping prices or a downward trend can signal worry on the part of investors. This can result in more selling and even lower prices. High trading volume could also reflect some isolated news or event related to the company associated with the stock.

Is Low Volume Bullish or Bearish?

Trading volume is defined as the number of shares traded in a particular period of time. So, low trading volume can indicate a lack of interest in either buying or selling. That means it could be bullish if low volume occurs in a downtrend. It could be bearish if it's noted in an uptrend.

Charles Schwab. " Trading Volume as a Market Indicator ."

Fidelity. " Turn Up the Volume on Stocks. "

Strategy & Education

Stock Trading Strategy & Education

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Nov 18, 2020

The Impact Closing Auctions Have on Volumes

By Matthew Healey, Analyst, and Cboe Global Markets’ Execution Consulting Team

Closing Time

Closing Auction Events by Exchange

Volume Trends Near the Close

In order to show the nature of volumes heading into the close, we zoomed in on trading during the last 30 minutes of the last 21 trading days. We found that volume trends across the four listing markets analyzed are very similar and react to many of the same events. It is important to note the key times and events during the closing auction, since cutoffs and imbalance dissemination vary by listing exchange. Figure 3 depicts the percent of total volume from 3:30 p.m. to 4 p.m. on each listing exchange and shows there are significant upticks in volume during the closing auction events on each exchange. The events listed in Figure 2 above, drive the percentage of total volume for all listing exchanges to increase up until the final seconds of the trading day. During that time, each exchange experiences a spike in volume almost five times greater than continuous trading volumes throughout the rest of the regular trading session.

Transaction Rate Near the Close

Spreads Near the Close

The increased level of information available near the close, due to the events described above, equips market participants to make more informed trading decisions. This increased information is also associated with higher urgency since the continuous session is near its end. This urgency makes it critically important for market participants to pick venues that have faster transaction rates. In a past note , we highlighted how EDGX provides faster fills and transaction rates than its peer exchanges.8 In this type of environment, trading flexibility is key, which is why Cboe plans to propose changes to the BZX close time cutoffs to allow participants to benefit from the higher volume and added information seen pre-close. By doing so, participants may also benefit from the increased liquidity environment, without having to commit quantity to the closing print.

Contact your Cboe Global Markets coverage team to learn more about how these changes may help you enhance your execution.

Footnotes 1, 5, 6, 7 Source: Cboe Market Data Footnote 2 Source: Nasdaq Footnote 3 Source: NYSE Footnote 4 Source: NYSE Arca Footnote 8 Source: Cboe

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Medical vocabulary: What does Closing Volume mean
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COMMENTS

Lung Closing Volume - an overview | ScienceDirect Topics
Closing volume is the volume towards the end of a forced expiration, after which some airways have effectively closed and more of the expired gas comes more from the relatively poorly ventilated regions of the lung. Closing capacity is the volume of gas within the lungs at the point at which airways closure begins.
Lung Closing Volume - an overview | ScienceDirect Topics
On an individual patient basis, the closing volume is most helpful in its relationship to the lung volume at which tidal breathing occurs. When airway closure occurs at a volume below FRC, the airways are open throughout the lungs during tidal breathing, but when airway closure occurs above FRC, the affected alveoli are underventilated.
Is a Stock's Trade Volume Important? - Investopedia
A high-volume stock, such as the aforementioned BAC, often has a tight bid-ask spread of a penny, which should do you minimal to no harm. When you look at daily trading volume, don’t just look ...
Clinical significance and measurement of closing capacity
The signficance of closing capacity is: Higher CC decreases the effect of pre-anaesthetic preoxygenation Higher CC increases dependent atelectasis It is responsible for the age-related decrease in oxygenation, because of shunt It aggravates lung injury through cyclic atelectasis
Anaesthesia UK : Physiology of ventilation - FRCA
FRC usually remains greater than closing volume, but closing volume slowly increases with age. In the supine position, closing volume exceeds FRC by the mid-40s, and in the erect position by 60 years of age. The reduction in FRC during general anaesthesia reduces FRC below closing volume even earlier, so young patients may have increased V/Q ...
Closing Capacity vs Closing Volume - CHEST
Closing Capacity vs Closing Volume. In an article in Chest (64:495-499, 1973), Dr. Buist repeated her claim that closing capacity (specifically, CC/TLC) is “of significantly greater sensitivity” than closing volume (specifically CV/VC) in the early detection of airway obstruction. This claim was supported by her Figure 3, a N2-CV record of ...
The Impact Closing Auctions Have on Volumes
In addition to studying closing volume trends, we found it important to analyze a transaction rate calculated as the amount of transactions per second on each listing exchange. We took a simple average of total transactions on each exchange over the same 21-day trading period used before.
Trading Volume: Analysis and Interpretation - Investopedia
Essentially, trading volume can legitimize a security's price action, which can then aid an investor in their decision to either buy or sell that security. 1 Key Takeaways Trading volume is the...
The Impact Closing Auctions Have on Volumes - Medium
It is important to note the key times and events during the closing auction, since cutoffs and imbalance dissemination vary by listing exchange. Figure 3 depicts the percent of total volume from 3:30 p.m. to 4 p.m. on each listing exchange and shows there are significant upticks in volume during the closing auction events on each exchange.