Money flow index
How recent volume went into up-moves versus down-moves, from -1 (all down) to +1 (all up).
MFI multiplies each bar's typical price (the average of its high, low and close) by its volume to get money flow. A bar whose typical price rose adds that flow to an up total, and a bar whose typical price fell adds it to a down total. Over the last window bars it reports the up total's share of all flow, rescaled to -1 to +1, which is the classic 0 to 100 Money Flow Index with 50 moved to zero. Because each bar is weighted by volume, one heavy bar can outweigh many light ones.
How to read it
- The line sits in its own pane below the price and stays between -1 and +1.
- 0 means rising and falling bars carried equal volume-weighted flow over the window.
- Above +0.6 (the classic 80 level) about 80% of the flow sat in rising bars; below -0.6 (the classic 20 level) about 80% sat in falling bars.
- Watch the turn back out of a zone rather than the zone itself.
What it outputs
- MFI
- Share of the window's volume-weighted flow sitting in rising bars, rescaled from -1 (all falling) to +1 (all rising).
Settings
- Window
- How many recent bars the up and down totals cover. Lowering it (7) makes the line jumpier and it reaches the extremes on short bursts of volume. Raising it (50 to 390) slows the line, so it reaches the extremes less often.
Pitfalls
- A window with no falling-bar volume, such as zero volume or a price that never moved, reads exactly +1.
- One heavy-volume bar stays in the totals for the full window and can flip the reading on its own.
- Extremes are not rare on one-minute bars: in the one-month SPY sample the top 5% of readings were above +0.80 and the bottom 5% below -0.77, so an extreme reading alone is not a reversal call.