Initial Balance (IB)

Session-opening high / low established over the first N bars of a session. Tracks the running session high and session low across the first period candles since construction or reset(). Once the period-th candle has been ingested the value is frozen and every subsequent call returns the same locked output until reset() is invoked.

Quick reference

Item	Value
Family	Market Profile
Input type	Candle (uses high, low)
Output type	InitialBalanceOutput { high, low }
Output range	unbounded (price-units)
Default parameters	period = 12 (1-hour IB on 5-minute US equity bars)
Warmup period	period
Interpretation	Session opening-balance zone; breaks signal trend day

Formula

For the first `period` candles since reset:
  high = running max
  low  = running min

After bar `period`:
  high, low locked until reset()

Caller is responsible for invoking reset() at each new session boundary. See crates/wickra-core/src/indicators/initial_balance.rs.

Parameters

Name	Type	Default	Constraint	Description
period	usize	12	> 0	Number of bars defining the IB window.

InitialBalance::new returns Error::PeriodZero for period == 0. InitialBalance::classic() returns the 12-bar factory.

Inputs / Outputs

Indicator<Input = Candle, Output = InitialBalanceOutput> with two fields (high, low).

• Python. InitialBalance(period).batch(high, low) returns an (n, 2) array. Note: batch mode is most useful for session- aggregated bars; on continuous data the locked behaviour produces constant output post-warmup.
• Node. Flat number[] of length n * 2.

Warmup

warmup_period() == period. First period - 1 bars return None; bar period emits and locks the value.

Edge cases

• No automatic reset. This is the most important caveat — must reset() at session boundaries manually.
• Lock-in semantics. Post-warmup output is constant until reset.
• Reset. Clears the running high/low and the lock.

Examples

Rust

use wickra::{Candle, InitialBalance, Indicator};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let bars = [
        Candle::new(100.0, 102.0, 99.0, 101.0, 10.0, 0)?,
        Candle::new(101.0, 103.0, 100.0, 102.0, 10.0, 1)?,
        Candle::new(102.0, 104.0, 101.0, 103.0, 10.0, 2)?,
    ];
    let mut ib = InitialBalance::new(3)?;
    for b in bars { let _ = ib.update(b); }
    let v = ib.value().unwrap();
    println!("IB high={}, low={}", v.high, v.low);  // 104, 99
    Ok(())
}

Python

import numpy as np
import wickra as ta

# 3-bar IB
h = np.array([102.0, 103.0, 104.0, 105.0, 106.0])
l = np.array([ 99.0, 100.0, 101.0, 102.0, 103.0])

ib = ta.InitialBalance(3)
out = ib.batch(h, l)
# After bar 3: IB locked at high=104, low=99
print(out[-1])  # [104.0, 99.0]

Node

const wickra = require('wickra');
const ib = new wickra.InitialBalance(3);
console.log(ib.batch([102, 103, 104, 105, 106], [99, 100, 101, 102, 103]));

Streaming with session reset

use wickra::{Candle, InitialBalance, Indicator};

let mut ib = InitialBalance::classic();  // 12-bar IB
let candle_stream: Vec<wickra::Candle> = Vec::new(); // your live OHLCV candle feed
fn is_new_session(_bar: Candle) -> bool { false } // your session-boundary predicate
for bar in candle_stream {
    if is_new_session(bar) {
        ib.reset();
    }
    if let Some(v) = ib.update(bar) {
        // IB high/low — use as breakout reference
    }
}

Interpretation

• IB as breakout reference. Price breaking above IB-high signals an "extension up" — trend-day potential. Breaking below IB-low signals an "extension down".
• Day-type classification. Market Profile traders use IB extension patterns to classify the day type (normal, trend-day, neutral, etc.).
• Default 12 bars. 1-hour IB on 5-min bars is the US equity convention. Other markets: 30-min IB (6 bars) for futures, configurable for crypto / FX.

Common pitfalls

• Forgetting reset. Without manual reset on session boundaries, the IB locks forever. Make session-boundary reset explicit in your trading loop.
• Wrong session definition. US equity RTH = 9:30-16:00 ET. Crypto 24/7 has no natural session; use UTC midnight or any consistent boundary.

References

• J. Peter Steidlmayer's Market Profile work (1980s) — origin of the Initial Balance concept.
• Jim Dalton, Mind Over Markets (1990) — practitioner treatment.

See also

• OpeningRange — shorter cousin with breakout-distance output.
• ValueArea — session volume distribution.
• Indicators-Overview — full taxonomy.