TD Countdown

The second half of DeMark's TD Sequential, packaged as a standalone indicator. Runs the 9-bar setup detection internally and then exposes only the countdown count (and direction). Useful when callers only need the countdown value and not the running setup state — smaller streaming payload than TdSequential.

Quick reference

Item	Value
Family	DeMark
Input type	Candle (uses high, low, close)
Output type	f64 — signed countdown count
Output range	[-countdown_target, +countdown_target]
Default parameters	(4, 9, 2, 13) — Setup (4, 9), Countdown (2, 13)
Warmup period	max(setup_lookback, countdown_lookback) + 1
Interpretation	+13 = buy countdown complete; −13 = sell countdown complete

Formula

Setup phase (internal, same as TdSetup):
  buy_setup advances on close[i] < close[i - setup_lookback]
  sell_setup advances on close[i] > close[i - setup_lookback]
  arms countdown on setup completion (setup_count == setup_target)

Buy countdown phase (after a buy setup completion):
  advances on close[i] <= low[i - countdown_lookback]
  (bars need not be consecutive)
  saturates at countdown_target

Sell countdown phase (mirror):
  advances on close[i] >= high[i - countdown_lookback]

Opposite-direction setup completion invalidates the active countdown.

Output:
  + buy_countdown    if buy direction active
  - sell_countdown   if sell direction active
  0                  if no countdown armed

See crates/wickra-core/src/indicators/td_countdown.rs.

Parameters

Name	Type	Default	Description
setup_lookback	usize	4	Setup-phase close-vs-close lookback.
setup_target	usize	9	Setup count needed to arm countdown.
countdown_lookback	usize	2	Countdown-phase close-vs-high/low lookback.
countdown_target	usize	13	Countdown target (DeMark's classic).

TdCountdown::new returns Error::PeriodZero for any zero argument. TdCountdown::classic() returns (4, 9, 2, 13).

Inputs / Outputs

Indicator<Input = Candle, Output = f64>. Python: TdCountdown(...).batch(high, low, close) returns a 1-D np.ndarray with NaN for warmup. Node: same shape; update(candle) returns number | null.

Warmup

warmup_period() == max(setup_lookback, countdown_lookback) + 1. For classic params, that's 5.

Edge cases

• Countdown can sit at a partial value. A countdown count of 7/13 may sit across many bars while waiting for the next qualifying close.
• Opposite-direction setup invalidates. A buy setup completion while a sell countdown is active resets the sell countdown to zero in the buy direction (re-arming).
• No countdown armed. Output is 0.0 when no countdown is active in either direction.
• Reset. reset() clears all internal state.

Examples

Rust

use wickra::{BatchExt, Candle, Indicator, TdCountdown};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let prices: Vec<f64> = (0..50).map(|i| 100.0 - f64::from(i) * 0.5).collect();
    let candles: Vec<Candle> = prices
        .iter()
        .enumerate()
        .map(|(i, &c)| Candle::new(c, c + 0.3, c - 0.3, c, 1.0, i as i64).unwrap())
        .collect();
    let mut td = TdCountdown::classic();
    let out = td.batch(&candles);
    println!("max buy countdown reached: {}",
             out.iter().flatten().fold(0.0f64, |a, &b| a.max(b)));
    Ok(())
}

Python

import numpy as np
import wickra as ta

# Sustained downtrend → buy countdown should complete (13)
close = 100 - np.arange(50, dtype=float) * 0.5
td = ta.TdCountdown(4, 9, 2, 13)
out = td.batch(close + 0.3, close - 0.3, close)
print('max:', np.nanmax(out))

Node

const wickra = require('wickra');
const td = new wickra.TdCountdown(4, 9, 2, 13);
const close = Array.from({ length: 50 }, (_, i) => 100 - i * 0.5);
const out = td.batch(close.map(c => c + 0.3), close.map(c => c - 0.3), close);
console.log('max:', Math.max(...out.filter(x => x != null)));

Streaming

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

let mut td = TdCountdown::classic();
let candle_stream: Vec<wickra::Candle> = Vec::new(); // your live OHLCV candle feed
for bar in candle_stream {
    if let Some(v) = td.update(bar) {
        if v == 13.0 { /* buy countdown complete */ }
        if v == -13.0 { /* sell countdown complete */ }
    }
}

Interpretation

• Countdown 13. The canonical DeMark exhaustion signal — high-conviction mean-reversion entry. Pair with TDST lines for stop placement.
• Countdown progress. A countdown of 8/13 is informational — it shows trend exhaustion is building but not complete. Some systems take entries on Countdown 12 + price confirmation.
• Vs TdSequential. Same trade logic; this indicator omits the running setup count from the output to save bandwidth. Use TdSequential when both pieces are needed.

Common pitfalls

• Treating Setup 9 as the countdown signal. Setup 9 just arms the countdown; the trade signal is Countdown 13.
• Resetting on session boundaries. Like TdSetup, this indicator should not be reset on session boundaries.
• Missing the invalidation. A countdown can be invalidated by an opposite-direction setup completion. Watch the direction of the output, not just its magnitude.

References

• Tom DeMark, The New Science of Technical Analysis (1994) — original Countdown formulation.
• DeMark on Day Trading Options (1999) — refined edge-case rules.

See also

• TdSetup — Setup-only variant.
• TdSequential — both Setup and Countdown emitted together.
• TdCombo — stricter, faster countdown variant.
• TdLines — TDST support / resistance.
• Indicators-Overview — full taxonomy.