A Renko Turnaround Black Brick is the first black brick after a series of white bricks. Renko charts are built from bricks of a fixed size that ignore time and small price moves: a white brick is added when the price rises by one brick size, a black brick when it falls by one brick size. Because a reversal needs a move of at least two brick sizes against the trend, the turnaround brick is a filtered signal that an advance may be ending.
