Directional Movement Index (DMI) Components: DI+ and DI-
The Directional Movement Index (DMI) quantifies trend strength and direction. J. Welles Wilder developed DMI. It consists of three primary lines: the Positive Directional Indicator (DI+), the Negative Directional Indicator (DI-), and the Average Directional Index (ADX). This lesson focuses on DI+ and DI-. These components measure buying and selling pressure. They provide context for price movement. DI+ represents the strength of upward price movement. DI- represents the strength of downward price movement.
Wilder's calculation for DI+ and DI- involves True Range (TR) and Directional Movement (DM). True Range measures market volatility. It takes the greatest value of:
- Current High minus Current Low
- Current High minus Previous Close (absolute value)
- Current Low minus Previous Close (absolute value)
Directional Movement determines if a bar is "up" or "down." +DM (Positive Directional Movement) occurs when the current High exceeds the previous High. The value is the current High minus the previous High. If the current Low minus the previous Low is greater, or if the current High is less than the previous High, +DM is zero. -DM (Negative Directional Movement) occurs when the current Low falls below the previous Low. The value is the previous Low minus the current Low. If the current High minus the previous High is greater, or if the current Low is greater than the previous Low, -DM is zero.
Wilder applies a smoothing technique to both +DM and -DM. This typically involves a 14-period exponential moving average (EMA). The smoothed values are then divided by the smoothed True Range to normalize them. DI+ = (Smoothed +DM / Smoothed TR) * 100 DI- = (Smoothed -DM / Smoothed TR) * 100
These lines oscillate between 0 and 100. A higher DI+ value indicates stronger buying pressure. A higher DI- value indicates stronger selling pressure. The crossover of DI+ and DI- generates trading signals.
Interpreting DI+ and DI- Crossovers
Crossovers between DI+ and DI- signal shifts in market control. A bullish signal occurs when DI+ crosses above DI-. This suggests buyers gain control. A bearish signal occurs when DI- crosses above DI+. This suggests sellers gain control.
Consider a 5-minute chart of ES (S&P 500 E-mini futures). On October 26, 2023, at 9:35 AM EST, ES trades near 4190. DI+ (14) crosses above DI- (14). DI+ reads 32.7, DI- reads 28.1. This crossover suggests an emerging uptrend. A trader might consider a long entry at 4190.50. An initial stop loss could be placed below the recent swing low, perhaps at 4187.00. This risk defines 3.5 points, or $175 per contract. A target might be the previous resistance level at 4197.50. This offers 7 points, or $350 per contract. The R:R ratio is 2:1. A 5-contract position risks $875 for a potential gain of $1750. By 10:15 AM EST, ES reaches 4198.00, hitting the target. DI+ remains above DI-.
Conversely, a bearish crossover occurred on November 2, 2023, at 10:00 AM EST, on the NQ (Nasdaq 100 E-mini futures) 15-minute chart. NQ trades near 14450. DI- (14) crosses above DI+ (14). DI- reads 35.2, DI+ reads 29.8. This crossover suggests an emerging downtrend. A trader might consider a short entry at 14449.00. An initial stop loss could be placed above the recent swing high, perhaps at 14460.00. This risk defines 11 points, or $220 per contract. A target might be the previous support level at 14427.00. This offers 22 points, or $440 per contract. The R:R ratio is 2:1. A 3-contract position risks $660 for a potential gain of $1320. By 11:00 AM EST, NQ reaches 14425.00, hitting the target. DI- remains above DI+.
These examples illustrate the direct application of DI+ and DI- crossovers. However, relying solely on crossovers proves insufficient. False signals frequently occur in choppy or range-bound markets.
Limitations and Institutional Context
DI+ and DI- crossovers generate false signals in sideways markets. When price consolidates, DI+ and DI- often crisscross around the 20-30 level. This creates whipsaws and generates losing trades. For instance, on a 1-minute chart of AAPL, during a lunch-hour consolidation from 12:00 PM to 1:00 PM EST, DI+ and DI- might cross five or six times. Price moves within a 50-cent range. Each crossover signal generates a small loss.
Institutional traders and algorithms rarely use DI+ and DI- in isolation. They integrate these indicators into broader trend-following systems. Prop firms often use DMI as a component of their proprietary trend identification algorithms. These algorithms typically combine DMI with volume analysis, moving averages, and volatility measures.
For example, a quantitative hedge fund might employ an algorithm that triggers a long entry only when:
- DI+ crosses above DI-.
- ADX (Average Directional Index) is above 25, confirming a strong trend.
- Volume exceeds the 20-period average by 20%.
- Price trades above the 50-period EMA.
This multi-factor approach filters out many false signals. Without ADX confirmation, a DI+ crossover might indicate a weak, short-lived price fluctuation. ADX measures trend strength. A low ADX (typically below 20) suggests a non-trending market. In such conditions, DI+ and DI- crossovers are unreliable.
Consider the ES example from October 26, 2023. At the 9:35 AM EST long entry, if ADX was below 20, a prop trader would likely ignore the DI+ crossover. The market might be consolidating. The ADX reading for that period was 38.5, confirming a strong trend. This confirms the validity of the DI+ crossover signal.
Similarly, for the NQ short entry on November 2, 2023, at 10:00 AM EST, the ADX reading was 42.1. This strong ADX value supported the bearish DI- crossover. If ADX had been 18.0, the signal would be disregarded.
Algorithms at institutions also use DI+ and DI- to manage existing positions. If an algorithm holds a long position in TSLA and DI- crosses above DI+, it might trigger a partial profit-take or a tightening of the stop-loss. This proactive risk management reduces exposure during potential trend reversals. They do not necessarily exit the entire position immediately. The crossover acts as an alert for increased vigilance.
Another institutional application involves divergence. If TSLA makes a higher high, but DI+ makes a lower high, it signals weakening buying momentum. This bearish divergence suggests a potential reversal. Algorithms monitor for such divergences across multiple timeframes (e.g., 15-min and 60-min charts) to identify high-probability turning points.
For instance, on a daily chart of CL (Crude Oil futures), if price makes a new high at $85.00, but DI+ only reaches 45 while its previous high was 55 at $83.00, this divergence indicates waning upward momentum. A prop trader might reduce long exposure or initiate small short positions, anticipating a correction.
DI+ and DI- also find utility in commodity trading firms. For GC (Gold futures), large institutions analyze DI+ and DI- on daily and weekly charts. A sustained period where DI+ remains significantly above DI- (e.g., DI+ > 40, DI- < 15) indicates a strong uptrend. These firms might scale into long positions, using pullbacks towards the 20-period EMA as entry points, while DI+ maintains dominance. Conversely, a prolonged period of DI- dominance (e.g., DI- > 40, DI+ < 15) signals a strong downtrend, prompting short accumulation.
The effectiveness of DI+ and DI- improves dramatically when combined with other indicators and market context. Volume, support/resistance levels, moving averages, and ADX provide essential filters. Without these filters, DI+ and DI- become noisy and unreliable, especially for high-frequency day trading.
Optimizing DI+ and DI- for Day Trading
Experienced day traders adjust the lookback period for DI+ and DI- based on volatility and timeframe. Wilder's default 14 periods works well for daily charts. For 1-minute or 5-minute charts, a shorter period like
