Trade Volume Index refines the relationship between price and volume by introducing a threshold filter. Unlike OBV which responds to any price change, TVI only changes direction when price movement exceeds a minimum tick threshold. This "sticky direction" behavior filters out noise from insignificant price fluctuations, allowing the indicator to better capture genuine accumulation and distribution.
The insight behind TVI is that small price movements within the bid-ask spread or normal market noise shouldn't flip the volume attribution. Only when buyers or sellers demonstrate enough conviction to move price beyond a meaningful threshold should the volume be credited to that side.
## Historical Context
Trade Volume Index was developed by William Blau and described in his work on technical analysis. Blau was known for developing indicators that filter market noise while preserving meaningful signals. TVI emerged from the recognition that OBV's sensitivity to any price change—even a single tick—could create false signals in choppy or range-bound markets.
The indicator gained popularity among futures and forex traders where minimum tick sizes are well-defined and market noise within the spread is common. By requiring price to exceed the minimum tick before changing direction, TVI:
- Filters out bid-ask bounce noise
- Reduces whipsaws in ranging markets
- Maintains direction during consolidation phases
- Provides cleaner divergence signals than OBV
The "sticky direction" concept means that once TVI establishes a direction (up or down), it maintains that bias until price convincingly moves the other way—exceeding the minimum tick threshold in the opposite direction.
## Architecture & Physics
TVI operates as a directional accumulator with hysteresis. The direction state is "sticky"—it persists through small price movements and only flips when price change exceeds the minimum tick threshold.
This creates a filtered money flow indicator that ignores noise and only responds to meaningful price movements.
### Component Breakdown
1.**Price Change Calculation**: Current close minus previous close
2.**Threshold Comparison**: Is |price_change| > minTick?
3.**Direction Update**: Flip direction only if threshold exceeded
4.**Volume Accumulation**: Add or subtract based on current direction
### State Requirements
| Component | Type | Purpose |
| :--- | :--- | :--- |
| TviValue | double | Current cumulative TVI |
| PrevPrice | double | Previous bar's close for comparison |
| Direction | int | Current direction: +1 (up) or -1 (down) |
| LastValidPrice | double | Fallback for NaN/Infinity handling |
| LastValidVolume | double | Fallback for NaN/Infinity handling |
## Mathematical Foundation
### Direction Logic
$$
\Delta P_t = Close_t - Close_{t-1}
$$
$$
Direction_t = \begin{cases}
+1 & \text{if } \Delta P_t > minTick \\
-1 & \text{if } \Delta P_t < -minTick \\
Direction_{t-1} & \text{otherwise (sticky)}
\end{cases}
$$
### TVI Formula
$$
TVI_t = TVI_{t-1} + Direction_t \times Volume_t
$$
where:
- $TVI_0 = 0$ (starts at zero)
- $Direction_0 = +1$ (default up)
- $minTick \geq 0$ (threshold parameter)
### Key Difference from OBV
| Aspect | OBV | TVI |
| :--- | :--- | :--- |
| Direction change | Any price difference | Only if \|Δprice\| > minTick |
| Unchanged price | Volume ignored (0) | Volume added with current direction |
| Small movements | Flip-flop possible | Direction is sticky |
| Parameter | None | minTick threshold |
### Why Sticky Direction?
The sticky direction behavior creates hysteresis—a form of memory that resists rapid direction changes. This is analogous to a Schmitt trigger in electronics, which prevents oscillation by requiring the input to cross a threshold before changing state.
Benefits:
- Filters bid-ask bounce in tick data
- Reduces noise in ranging markets
- Maintains trend bias during minor retracements
- Produces smoother divergence signals
## Performance Profile
### Operation Count (Streaming Mode)
| Operation | Count | Notes |
| :--- | :---: | :--- |
| SUB | 1 | price_change = close - prevClose |
| CMP | 2 | price_change > minTick, < -minTick |
| MUL | 1 | direction × volume |
| ADD | 1 | Cumulative TVI update |
| **Total** | 5 | Per bar, O(1) |
TVI has slightly more operations than OBV due to threshold comparisons, but remains extremely lightweight.
### Batch Mode (SIMD)
| Operation | Vectorizable | Notes |
| :--- | :---: | :--- |
| Price differences | ✅ | Close[i] - Close[i-1] |
| Threshold comparisons | ✅ | ConditionalSelect |
| Direction update | ❌ | Sequential dependency (sticky) |
The sticky direction state creates a sequential dependency that prevents full SIMD vectorization. However, price difference calculations can be vectorized as a preprocessing step.
### Quality Metrics
| Metric | Score | Notes |
| :--- | :---: | :--- |
| **Accuracy** | 10/10 | Exact computation |
| **Timeliness** | 7/10 | Threshold delays response to small moves |
| **Noise Filtering** | 9/10 | Sticky direction filters noise well |
| **Overshoot** | N/A | No bounds; cumulative indicator |
| **PineScript** | ✅ | Custom implementation available |
TVI is not a standard indicator in most libraries. QuanTAlib implementation is based on Blau's original specification and validated against the PineScript reference implementation. Internal consistency between streaming, batch, and span modes is verified with tight tolerances (1e-9).
## Common Pitfalls
1.**MinTick Selection**: Choosing an appropriate minTick value is critical. Too small reduces TVI to OBV behavior; too large makes direction changes rare. For stocks, 0.01–0.10 is typical. For futures, use the contract's minimum tick size.
2.**Absolute Value Meaningless**: Like OBV, TVI's numeric value has no intrinsic meaning—only direction and divergences matter. Don't compare TVI values across different securities.
3.**Not Bounded**: TVI can reach any value, positive or negative. It has no overbought/oversold levels. Use trend analysis, not absolute thresholds.
4.**Default MinTick**: The default minTick of 0.125 (1/8) was historical for stock trading in eighths. Modern decimalized markets may need adjustment.
5.**Zero MinTick**: Setting minTick = 0 makes TVI behave similarly to OBV, but not identically—TVI adds volume even on unchanged prices (using the sticky direction), while OBV adds zero.
6.**Initial Direction**: TVI starts with direction = +1 (up). The first bar's volume is always added positively. This matches standard implementations.
7.**TValue Limitations**: The `Update(TValue)` method exists for interface compatibility but cannot compute TVI properly without volume data. Use `Update(TBar)` for proper calculation.
8.**isNew Parameter**: When correcting bars (isNew=false), the implementation properly restores previous state including direction. Incorrect handling causes cumulative drift.
## Interpretation Guide
### Trend Confirmation
| Price Trend | TVI Trend | Interpretation |
| :--- | :--- | :--- |
| Rising | Rising | Confirmed uptrend with filtered volume support |
| Falling | Falling | Confirmed downtrend with filtered volume support |
