//@version=6
indicator("MARKETFI: Market Facilitation Index", shorttitle="MARKETFI", overlay=false)

// Bill Williams' Market Facilitation Index (BW MFI)
// Measures price movement efficiency per unit of volume.
// High MFI + rising volume = strong trend (green)
// Low MFI + falling volume = squat / accumulation (brown)
// Guard: volume == 0 produces 0.0 (no market activity = no MFI)

mfi = volume != 0 ? (high - low) / volume : 0.0

plot(mfi, title="MARKETFI", color=color.blue, linewidth=2)
hline(0, "Zero", color=color.gray, linestyle=hline.style_dashed)