A Renko Long Tail Down Reversal is a turn up after a long, uninterrupted run of black 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. A steep decline without any rebound often leaves the stock oversold, so the first white bricks after it can mark a sharp reversal higher.
