Open types and day types

The first thirty to sixty minutes of a session reveal a great deal about what kind of day it will be. Auction theory has names for the common opening patterns and for the day types they tend to produce. Knowing them gives you a prior before the day has unfolded, which is worth more than any single trade.

Where the open sits

Before classifying the open itself, note where it happened relative to yesterday's value:

Open location	Meaning	Prior
Inside yesterday's value area	Market agrees with yesterday; balance likely	Rotation, lower conviction
Outside value but inside yesterday's range	Mild disagreement	Watch for a return to value or acceptance outside it
Outside yesterday's range (gap)	Overnight repricing	Higher conviction; trend day more likely, especially if the gap is not filled early

An open outside range that holds is the strongest setup for a trend day. An open inside value that stays there is the strongest setup for a rotation day.

The four open types

Open-drive. Price moves directly away from the open with conviction and does not return to the opening price. The footprint shows stacked imbalances in the drive direction from the first bar. Delta is strongly one-sided. This is the highest-conviction open: participants had a decision made before the bell.

  Open-drive (up)
  Bar:   1    2    3    4    5    6
  High  5004 5007 5010 5012 5014 5015
  Low   5000 5003 5006 5009 5011 5013
  Delta +410 +380 +520 +290 +340 +210
  Opening price 5000 never revisited

Open-test-drive. Price briefly tests one direction (often toward a reference such as yesterday's close or a prior level), fails to find business there, and then drives the opposite way with conviction. The test is short and the drive resembles an open-drive afterwards. Slightly lower conviction than a pure drive, but the test that failed gives you a clear stop reference.

  Open-test-drive (down after testing up)
  Bar:   1    2    3    4    5    6
  High  5003 5004 5001 4998 4995 4992
  Low   4999 5000 4996 4993 4990 4989
  Delta  +90 −140 −380 −450 −310 −260
  Tested 5004, found no buyers, drove down

Open-rejection-reverse. Price moves one way, meets strong responsive activity (absorption, a finished extreme), and reverses back through the open. Conviction is low; participants are undecided. Expect a wider, two-way opening period.

  Open-rejection-reverse
  Bar:   1    2    3    4    5    6
  High  5004 5006 5005 5002 5000 4999
  Low   5000 5003 5001 4998 4996 4995
  Delta +300 +120 −280 −340 −200 −150
  Drove up, got absorbed at 5006, reversed through 5000

Open-auction. Price rotates around the open with no direction. Delta alternates and is small. This is the lowest-conviction open and usually happens inside yesterday's value. Expect a balance day unless something arrives later.

  Open-auction
  Bar:   1    2    3    4    5    6
  High  5002 5003 5002 5003 5002 5004
  Low   4999 5000 4998 4999 4998 5000
  Delta  +60  −40  +80 −110  +30  −20

Key idea: The open type is a conviction reading. Drive means participants decided overnight; auction means they did not. Match your tactics to the conviction level before you take a single trade.

Day types

Open types tend to lead into day types, though the mapping is a tendency and not a rule.

Day type	Description	Typical open	Profile shape	Tactics
Trend day	One direction most of the day, closes near extreme	Open-drive or open-test-drive	Thin, elongated	Join pullbacks; never fade
Normal day	Wide initial balance, little extension either way	Open-auction	Bell	Fade the initial balance edges
Normal variation	Initial balance extended once in one direction	Open-auction then late initiative	Bell with a tail	Fade until extension; then join
Double distribution	Balance, then a fast move, then a new balance	Any; the move comes mid-session	Two bells with an LVN between	Trade the traverse; then fade the new balance
Neutral day	Extends both sides of initial balance, closes in the middle	Open-rejection-reverse	Wide bell	Fade both edges; small targets
Non-trend day	Very narrow, low volume	Open-auction	Tiny bell	Do not trade; or prepare for tomorrow's breakout

The initial balance, the range of the first hour, is the reference for most of these. Module 5 covers it in detail. For now, note that a wide initial balance suggests a normal or neutral day (the market found both sides quickly), and a narrow initial balance suggests a trend or normal-variation day (the market has not found one side yet and will need to search).

Numbers to keep

Three simple measurements at the end of the first hour set expectations for the rest of the day:

Measurement	Formula	Example	Read
Initial balance width	IB high − IB low	5012 − 5000 = 12 points	Compare to the 20-day median IB; narrow = trend more likely
Open location vs prior value	Open − prior POC	5001 − 5008 = −7	Opened below value; sellers had overnight conviction
First-hour delta ratio	Ask vol ÷ bid vol	18,400 ÷ 11,200 = 1.64	Buyers clearly more aggressive; supports a drive

None of these predicts the day. Together they give you a prior that you can update as the session unfolds, which is exactly what Module 6's playbook does.

A caution

Day types are named after the fact. A trend day is obvious at 3 pm and ambiguous at 10 am. The value of the classification is not to label the day early and trade the label; it is to know which tactics are compatible with which developing picture and to stop using the wrong ones. A trader who recognises by 10:30 that "this is not a fade day" has saved themselves the most expensive category of loss in profile trading.

Try it: For the last ten sessions on your product, record the open location (inside value, inside range, outside range), the open type, the initial balance width, and the day type as it turned out. Ten rows is enough to see whether your product has a tendency, such as "outside-range opens became trend days seven times out of eight." That is a prior you can use.

Recap

Note where the open sits relative to yesterday's value and range; outside-range opens carry more conviction.
Open types are conviction readings: open-drive (high), open-test-drive (high, after a short failed test), open-rejection-reverse (low), open-auction (lowest).
Day types (trend, normal, normal variation, double distribution, neutral, non-trend) follow from the open and the initial balance with tendencies, not rules.
Measure initial balance width, open distance from prior POC, and first-hour delta ratio to form a prior.
Use classification to exclude wrong tactics as the day develops, not to predict the day at the bell.