Money Flow Index (MFI)
A momentum oscillator that combines price and volume to measure buying and selling pressure, oscillating between 0 and 100. Often called a "volume-weighted RSI."
The Money Flow Index (MFI) is a technical indicator developed by Gene Quong and Avrum Soudack. It calculates a positive and negative money flow using the typical price ((high + low + close) / 3) multiplied by volume, then normalizes to a 0–100 oscillator over a lookback period — typically 14 periods.
Because MFI incorporates volume, it can detect situations where price is drifting on low participation, which are often less trustworthy than moves confirmed by heavy volume. Readings above 80 are traditionally considered overbought and readings below 20 oversold, but as with RSI, these thresholds are more useful as context than as signals.
For sector-rotation analysis, MFI at the ETF level reveals which sectors are being accumulated (rising price with strong volume) versus distributed (rising price on weak volume, or falling price on heavy volume). BullrunData exposes per-sector MFI plus a 20-day volume z-score via /api/v1/sectors/flows and classifies each sector as accumulation, distribution, or neutral based on both signals.