Volume Analysis Tools: OBV, VWAP, and Money Flow Index

Volume is the second dimension of every bar on a chart. Every candle shows price information (open, high, low, close) and volume information (how many shares or contracts traded during that bar). The candle and chart pattern lessons throughout this curriculum have referenced volume in passing — pattern statistics improve when volume confirms the pattern, breakouts are more reliable on heavy volume, divergence between price and volume warns of trend exhaustion — but we haven't yet covered the specific tools that turn volume into systematic analysis.

This lesson covers three foundational volume tools that the thinkorswim platform groups under Popular Studies and Market Strength Studies: On-Balance Volume (OBV), Volume-Weighted Average Price (VWAP), and Money Flow Index (MFI). These three tools answer different questions about volume. OBV tracks the accumulated buying versus selling pressure across time. VWAP shows the average price weighted by volume during a specific session. MFI combines volume with price to identify overbought and oversold conditions weighted by participation. Together they form the foundation of volume-based technical analysis.

When a reader adds these tools to a chart, several configurable parameters appear for each.

• OBV settings. OBV's calculation has no period parameter — it accumulates volume continuously from whenever the chart begins. The only configurable settings are visual (line color, line style). This makes OBV one of the simplest indicators to use: no settings to optimize, no parameters to second-guess.
• VWAP settings. Standard VWAP resets at the start of each trading session. Anchored VWAP allows the trader to specify an anchor point. Most platforms offer additional configurable bands around VWAP (typically 1, 2, and 3 standard deviations) that act similarly to Bollinger Bands but centered on VWAP rather than a moving average.
• MFI settings. Period (default 14, matching RSI's default), with the same considerations as RSI period selection. Overbought and oversold thresholds (defaults 80 and 20 rather than RSI's 70 and 30, reflecting MFI's tendency to reach more extreme readings). Some platforms allow customization of the typical price calculation, but the standard (H+L+C)/3 works for most applications.

OBV's calculation is conceptually simple but accumulates meaningful information across many bars.

Start with OBV = 0 at the chart's first bar. For each subsequent bar: if the close is higher than the prior close, add that bar's volume to OBV. If the close is lower than the prior close, subtract that bar's volume from OBV. If the close equals the prior close, OBV remains unchanged.

VWAP's calculation requires several pieces of data for each bar. For each bar in the session, calculate the typical price: (high + low + close) / 3. Multiply this typical price by the bar's volume to get the price-volume product. Sum the price-volume products from the session's start through the current bar. Sum the volumes from the session's start through the current bar. Divide the cumulative price-volume by cumulative volume:

MFI's calculation extends the RSI framework to incorporate volume.

Step 1: Calculate typical price for each bar: (high + low + close) / 3. Step 2: Calculate raw money flow for each bar: typical price × volume. Step 3: For each bar in the lookback period (default 14), classify the money flow as positive or negative based on whether the typical price rose or fell from the prior bar. Step 4: Sum positive money flows and sum negative money flows across the lookback period. Step 5: Calculate the money ratio: positive money flow sum / negative money flow sum. Step 6: Calculate MFI:

Each tool has specific reading habits that make it useful within integrated analysis.

• Reading OBV. Watch the direction of OBV relative to price. Confirming OBV (rising during rising prices, falling during falling prices) supports the trend. Diverging OBV warns of potential reversal. Look specifically for the bullish divergence pattern (price makes lower low, OBV makes higher low) and bearish divergence (price makes higher high, OBV makes lower high). These divergences often precede reversals by weeks or months on weekly charts.
• Reading VWAP. During the trading day, VWAP acts as a dynamic reference level. Price above VWAP suggests bullish bias for the session; price below suggests bearish bias. Bullish day traders often look for pullbacks to VWAP as long entry opportunities; bearish day traders look for rallies to VWAP as short entry opportunities. The VWAP bands (1, 2, 3 standard deviations) provide additional reference levels similar to Bollinger Bands.
• Reading MFI. Apply the same reading habits as RSI from Lesson 34, but recognize that MFI's volume weighting makes its signals more meaningful when volume has been varying significantly across bars. In low-volume periods where all bars have similar volume, MFI and RSI produce similar signals. In high-variance volume periods, MFI signals carry more information than RSI alone.
• Combining the volume tools. Many traders use OBV for trend confirmation, VWAP for intraday reference levels, and MFI for divergence detection. The three tools answer different questions and don't substantially overlap, so using them together is less of an indicator soup problem than stacking multiple momentum oscillators.

QuantifiedStrategies' backtest of OBV trading strategies on the S&P 500 showed 369 trades with an average gain per trade of 0.6%, a 75% win rate, maximum drawdown of 24%, and profit factor of 2.01. However, their research notes that volume as a standalone parameter has limited value — the strong win rate comes from specific OBV applications integrated with broader market context rather than from mechanical OBV signals.

ToSIndicators' research on volume indicators across 1,872 breakout events in 50 S&P 500 stocks from 2024-2026 found that relative volume readings of 1.5-2.0 produce the highest 3-day follow-through rates at 58.8%. This confirms that volume confirmation substantially improves breakout reliability, with optimal volume expansion (not too low, not extremely high) producing the best follow-through results.

Liberated Stock Trader's research on OBV finds that to improve OBV signal reliability, traders should pair it with RSI or MACD. OBV divergence — when price and OBV move in opposite directions — is described as the most useful OBV pattern, with bullish divergence (price drops but OBV rises) suggesting increasing buying pressure that could lead to upward price movement.

• Joseph Granville's original publications on OBV from the 1960s
• liberatedstocktrader.com — research on OBV and volume indicators
• quantifiedstrategies.com — backtested OBV strategies on multiple asset classes
• tosindicators.com — thinkorswim-specific research on volume tools
• Anna Coulling's 'A Complete Guide to Volume Price Analysis' — practical volume analysis methodology
• Academic literature via Google Scholar — search 'volume analysis,' 'On-Balance Volume,' 'VWAP execution'

• Treating OBV's absolute value as meaningful. OBV's specific number is arbitrary — it depends entirely on when the chart's history started. What matters is the direction of OBV across time and how that direction compares to price. Beginners sometimes try to interpret OBV's level (high OBV is bullish, low OBV is bearish) which is meaningless.
• Using VWAP on the wrong timeframe. VWAP resets at the start of each trading session, which makes it primarily a day trading tool. Using session VWAP on a weekly or monthly chart doesn't produce meaningful signals because the VWAP keeps resetting too frequently relative to the timeframe being analyzed. Anchored VWAP solves this by allowing the trader to choose meaningful anchor points.
• Treating MFI as identical to RSI. The volume weighting makes MFI's signals different from RSI's in specific situations. Strong moves on heavy volume push MFI more decisively than RSI; the same moves on light volume push MFI less. Traders who treat them as interchangeable miss the specific information MFI's volume weighting provides.
• Ignoring volume divergence entirely. OBV divergence is one of the most valuable signals the indicator provides. Many traders watch OBV's general direction without specifically looking for divergence patterns, missing the most useful signals.
• Adding all volume indicators to the same chart. OBV, VWAP, MFI, Chaikin Money Flow, Accumulation/Distribution, Volume Profile, and others can all be added simultaneously. They mostly measure similar things and stacking them produces indicator soup. Pick one or two that fit your specific use case.
• Trying to use VWAP as a standalone signal. Like all indicators, VWAP works better as part of integrated analysis than as a standalone trigger. 'Buy when price crosses above VWAP, sell when it crosses below' produces mediocre results when applied mechanically.

The integrated chart below follows the progressive integration principle. It includes candle patterns from Lessons 1-13, a chart pattern from Lessons 14-28, moving averages from Lesson 30, and the new OBV tool from this lesson — showing how volume analysis adds an additional dimension to the integrated reading.

Rounding bottom (Lesson 18) with hammer and morning star at the structural low, and OBV showing bullish divergence well before price confirms the reversal

This chart shows what the integrated reading looks like with OBV added below the price chart. The chart includes a rounding bottom pattern from Lesson 18, two named candle patterns from Lessons 1-13 (hammer and morning star), and OBV showing a clear bullish divergence well before price confirms the reversal.

The early decline (candles 1-12). Twelve bearish candles drive price down with steady directional pressure. OBV declines alongside price during this phase, confirming the downtrend — selling volume exceeds buying volume.

The decline slows (candles 13-18). Six more bearish candles continue the decline but with smaller bodies and less aggressive selling. The pace of OBV's decline slows even as price continues making new lows. This is the early development of the bullish divergence — selling volume is fading even as price extends downward.

The morning star development (candles 20-22). A three-candle morning star pattern completes. Bearish candle, then small-body indecision (candles 20 and 21), then strong bullish candle (candle 22). From Lesson 7, the morning star is one of the most reliable bullish reversal patterns. The OBV continues rising during this period, confirming that buying volume is increasing as price establishes the bottom.

The divergence developed gradually over many bars before any clear price reversal. A trader watching OBV would have early warning that the decline was structurally exhausting — buyers were quietly accumulating even while price kept making new lows. This is exactly the kind of advance signal that volume analysis provides that price-only analysis misses.

The recovery and breakout (candles 23-34). Twelve bullish candles drive price up through the right side of the rounding bottom, eventually approaching the rim resistance level. OBV continues rising throughout, confirming that volume supports the new uptrend. The combination of rounding bottom completion, named candle patterns at the structural low, and OBV bullish divergence provides multi-dimensional confirmation of the reversal.

What this integrated chart teaches together. Several pedagogical points emerge.

OBV divergence often precedes price reversals by many bars. The OBV started showing higher lows while price was still making lower lows. A trader watching only price would have seen continued bearish action; a trader watching OBV would have known buyers were quietly accumulating. The advance warning value of OBV divergence is what makes the indicator most useful.

Volume confirmation strengthens chart pattern reliability. The rounding bottom pattern alone would be a tradeable setup. The rounding bottom with OBV bullish divergence is a higher-conviction setup because two independent analytical dimensions agree.

Candle reversal patterns at structural moments combined with volume divergence create the highest-conviction signals. The hammer at the rounding bottom's structural low, occurring with OBV already showing bullish divergence, creates multi-layer confluence that warrants meaningful position sizing.

The volume tools integrate with everything the curriculum has built. Volume confirmation improves chart pattern reliability (Lessons 14-28 reference volume signatures repeatedly). Volume expansion on breakouts adds conviction to entries. Volume divergence on OBV or MFI warns of trend exhaustion that other indicators may miss. VWAP provides intraday support and resistance levels that interact with candle patterns and chart pattern structures.

Lesson 38 covers ADX (Average Directional Index) and Parabolic SAR — two tools specifically designed to measure trend strength and identify trend changes. With momentum and volume tools now covered, the trend strength tools complete the major analytical categories beyond moving averages. ADX in particular is widely used as a regime filter — distinguishing trending markets (where momentum and crossover signals work well) from ranging markets (where mean reversion signals work better).