Volume & money flowMarket Facilitation Index · BW MFI
Bill Williams' measure of price movement per unit of volume — how easily the market moves price.
Works in most conditionsEngine-computed on a fixed sample series
What it is
The Market Facilitation Index, often labeled BW MFI after its creator Bill Williams, measures how easily the market moves price for each unit of volume traded. The core question it asks is efficiency: for all the volume that changed hands in a bar, how much price movement did that volume actually produce? A bar where a lot of volume generated a wide price range means the market is facilitating price movement well, while a bar where heavy volume produced only a narrow range means the market is struggling to move despite plenty of activity. Williams then reads the index not in isolation but by comparing whether it and volume rose or fell together, sorting each bar into one of four named states. For a beginner, the MFI is a lens on the relationship between effort, meaning volume, and result, meaning price range.
How it is calculated
The calculation itself is disarmingly simple: the Market Facilitation Index equals the bar's range, the high minus the low, divided by the bar's volume, sometimes scaled by a constant for readability. This yields a value representing how much price travel one unit of volume purchased in that bar. The interpretive power comes not from the raw number but from comparing its change to the change in volume from the prior bar, which produces a two-by-two grid of possibilities. Each of the four combinations, index up or down paired with volume up or down, is given a color and a name that describes the market condition. So the tool is really the simple ratio plus a classification scheme layered on top, rather than a complex formula. Note that this Market Facilitation Index is entirely distinct from the similarly named Money Flow Index, which is a volume-weighted RSI.
Reading it, step by step
The four states are the heart of the reading. A Green bar, where both the index and volume rose, signals a lively, well-supported move with new participants driving price efficiently, confirming the current direction. A Fake bar, where the index rose but volume fell, warns that price is moving on thin participation and the move may not be genuine. A Squat bar, where the index fell but volume rose, marks a battle in which heavy volume produced little price movement, often a sign of a struggle that precedes a breakout, making it the most watched state. A Fade bar, where both the index and volume fell, reflects waning interest and a market losing energy, common at the end of a move. Reading the MFI is a matter of identifying which of these four conditions the latest bar represents and what it implies about coming price action.
Best timeframes and settings
The Market Facilitation Index has no lookback period to set, since each bar's value depends only on that bar's own range and volume, which makes it unusually parameter-free. It is most meaningful on timeframes and instruments where volume data is reliable and centralized, such as daily and intraday charts of stocks and futures. Williams applied it within his broader trading approach on the instruments he traded, and it transfers to any market with trustworthy volume. Because it is a per-bar reading rather than a smoothed series, it reflects immediate conditions and does not lag, but it also offers no trend context on its own. It is less useful on markets with fragmented or estimated volume, where the denominator of the ratio is unreliable, so the quality of the volume feed matters more than any setting.
When and where to use it
The Market Facilitation Index is a context tool rather than a signal generator, and it is best used to interpret the quality of price moves within a broader method, which is exactly how Bill Williams intended it as one component of his larger system. It suits volume-rich, liquid markets like stocks, futures, and centralized exchanges. It is most valuable when you want to judge whether a move has real backing, using Green bars to confirm energetic moves and watching Squat bars for impending resolutions. It is not designed to be traded alone and gives no directional call by itself. Avoid relying on it where volume data is poor, and avoid treating its color states as predictions rather than descriptions of current effort versus result.
Strategies that use it
The primary use is as confirmation context: when another part of your method signals a breakout or trend continuation, a Green MFI bar validates that the move has volume and range behind it, increasing your confidence to enter. A Squat-based approach watches for Squat bars, where high volume yields little movement, as an alert that a coiled battle is likely to resolve soon, prompting you to prepare an entry in the direction of the eventual break. A caution strategy uses Fake and Fade bars to filter out or exit moves that lack genuine participation, avoiding chasing price that is drifting on thin volume. In every case the MFI supplies the go or caution context while a separate tool supplies the direction and the trigger, because the index is interpretive rather than predictive.
Combining it with other indicators
Because the MFI describes volume-and-range quality but not direction, it pairs naturally with trend and momentum tools such as moving averages, the MACD, or Bill Williams' own Alligator and Awesome Oscillator, which supply the directional read. Cumulative volume tools like on-balance volume or cumulative volume delta corroborate whether accumulation or distribution accompanies the MFI states. Support and resistance levels give Squat bars a location to matter, since a Squat at a key level is a stronger breakout alert than one in open space. Price patterns and breakout levels combine with Green bars to confirm energetic follow-through. The consistent idea is to let the MFI grade the effort-versus-result quality of each bar while independent tools establish the direction and the levels worth trading around.
Where it fails
The MFI reduces an entire bar to a single ratio, so it can mislead around data quirks such as an unusually low-volume bar, which inflates the ratio, or a wide-range outlier that distorts it. Its color scheme is fundamentally descriptive, telling you what just happened to effort and result, not what will happen next, so treating the states as forecasts is a category error. Traders sometimes over-interpret a single Squat bar as a guaranteed breakout when it is only an alert that must still be confirmed by price. On instruments with unreliable volume the ratio is meaningless. The way to use it well is to treat it strictly as interpretive context within a larger, direction-giving method, to require volume data you trust, and never to trade its states mechanically as if they predicted the next move.
A worked example
A stock has been consolidating in a tight range near fifty for several days, and you are watching for a breakout. On one session price barely moves, closing with a narrow range of just thirty cents, yet volume surges well above average, so the Market Facilitation Index falls while volume rises, printing a Squat bar. You recognize this as a battle in which heavy volume produced little movement, a classic coil that often precedes a break, so you set alerts just above and below the range. Two sessions later price pushes up through fifty-one on expanding range and rising volume, printing a Green bar that confirms the breakout is energetic and well-supported. You enter long at fifty-one-twenty with a stop back inside the range at forty-nine-fifty, using the Squat as your heads-up and the Green bar as your confirmation, and price runs to fifty-six as the move follows through.