TD Sequential

The full Tom DeMark Sequential indicator: a Setup count followed by a Countdown count. Setup runs the 9-bar momentum-exhaustion gate, Countdown then runs a separate 13-bar confirmation; together a completed Sequential is the canonical DeMark exhaustion signal. Emits both phases in a single Output so the caller can read setup progress and countdown progress in one shot.

Quick reference

Item	Value
Family	DeMark
Input type	Candle (uses high, low, close)
Output type	TdSequentialOutput { setup, countdown: i32 } (signed: positive = buy, negative = sell)
Output range	setup ∈ [-setup_target, setup_target], countdown ∈ [-countdown_target, countdown_target]
Default parameters	setup_lookback=4, setup_target=9, countdown_lookback=2, countdown_target=13
Warmup period	max(setup_lookback, countdown_lookback) + 1
Interpretation	Buy (setup=9, countdown=13) or sell (-9, -13) signals momentum exhaustion

Formula

Setup phase — same as TdSetup:

if close[t] < close[t - setup_lookback]:  buy_setup_streak += 1
if close[t] > close[t - setup_lookback]:  sell_setup_streak += 1
streak resets on the opposite direction or on equality

Once buy_setup_streak == setup_target (9), the Countdown phase arms. From the next bar:

if close[t] <= low[t - countdown_lookback]:   buy_countdown += 1
if close[t] >= high[t - countdown_lookback]:  sell_countdown += 1

Countdown completes at countdown_target (13). See crates/wickra-core/src/indicators/td_sequential.rs.

Parameters

Name	Type	Default	Description
setup_lookback	usize	4	Setup-phase close-vs-close lookback.
setup_target	usize	9	Setup-phase target count (Setup 9).
countdown_lookback	usize	2	Countdown-phase close-vs-high/low lookback.
countdown_target	usize	13	Countdown-phase target count (Countdown 13).

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

Inputs / Outputs

Indicator<Input = Candle, Output = TdSequentialOutput>. TdSequentialOutput carries setup: i32 and countdown: i32, both signed (positive = buy-side counts, negative = sell-side).

• Python. Returns a (setup, countdown) 2-tuple per bar in an (n, 2) array.
• Node. Returns { setup, countdown } | null per bar; flat number[] of length n * 2 for batch.

Warmup

warmup_period() == max(setup_lookback, countdown_lookback) + 1 — fundamentally the same close-buffer requirement as TD Setup, just with both lookbacks available.

Edge cases

• Setup completes before Countdown can arm. Buy Setup 9 arms Buy Countdown; if a sell-side momentum bar then prints, the Buy Setup counter doesn't reset, but Buy Countdown bars don't increment either.
• Countdown interrupted. Countdown counts can sit at a partial value (e.g. 7/13) across many bars while waiting for the next qualifying close.
• Opposite-direction invalidation. A sell setup completion can invalidate an active buy countdown — output direction flips.
• Reset. reset() clears both setup and countdown streaks.

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let prices: Vec<f64> = (0..60).map(|i| 100.0 - f64::from(i) * 0.4).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 = TdSequential::classic();
    for c in &candles {
        if let Some(o) = td.update(*c) {
            if o.countdown == 13.0 { println!("buy countdown complete"); }
            if o.countdown == -13.0 { println!("sell countdown complete"); }
        }
    }
    Ok(())
}

Python

import numpy as np
import wickra as ta

close = 100 - np.arange(60, dtype=float) * 0.4
td = ta.TdSequential()
out = td.batch(close + 0.3, close - 0.3, close)
# out shape (60, 2): columns [setup, countdown]
print('row 30:', out[30])

Node

const wickra = require('wickra');
const td = new wickra.TdSequential();
const close = Array.from({ length: 60 }, (_, i) => 100 - i * 0.4);
const flat = td.batch(close.map(c => c + 0.3), close.map(c => c - 0.3), close);
console.log('row 30: setup =', flat[30 * 2], 'countdown =', flat[30 * 2 + 1]);

Streaming

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

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

Interpretation

• Buy Setup 9 → Buy Countdown 13. Capitulation-grade oversold — high-conviction long mean-reversion signal.
• Sell Setup 9 → Sell Countdown 13. Mirror — distribution topping signal.
• Setup 9 without Countdown 13. Momentum extreme but not the full DeMark setup-and-cool-off pattern. Still tradable as a short-term reversal setup, just with lower historical hit rate.
• Risk management. Pair with TdLines for invalidation levels and TdRiskLevel for protective stops.

Common pitfalls

• Trading on Setup 9 alone. Setup 9 is the gate, Countdown 13 is the entry. Mixing them up halves the signal's edge.
• Resetting Countdown manually on session boundaries. Sequential is bar-stream agnostic; do not reset on session boundaries.
• Ignoring direction. The signed output makes direction explicit; ignoring it produces inverted signals.

References

• Tom DeMark, The New Science of Technical Analysis (1994) — original full Sequential treatment.
• DeMark on Day Trading Options (1999) — recycle, deferred countdown, and other edge-case rules.

See also

• TdSetup — Setup-only variant.
• TdCountdown — Countdown-only variant.
• TdCombo — faster, stricter countdown variant.
• TdLines — TDST support/resistance lines.
• TdRiskLevel — protective-stop levels.
• Indicators-Overview — full taxonomy.