The Head-and-Shoulders Top pattern forms when a pair is testing new highs on an uptrend, but fails to retest its highest high and break upward. Mounting selling pressure takes over each time a pair approaches its high. The pattern forms with a center peak (the Head, labeled 3) and left and right Shoulders (1, 5). Eventually the pair stops testing highs and reverses trend into a decline.
Consider selling the pair short before it declines or buying a put option to benefit from the price decline. To improve success chances, wait for a confirmation move: allow the price to break below the Neckline level (2, 4), which is calculated as the average of the two lows between the Head and the Shoulders. To estimate an exit, calculate the pattern height by taking the price difference between the Head (3) and the Neckline price (4), and subtract that from the Neckline price level/breakout price level.
To limit potential loss when price suddenly goes in the wrong direction, consider placing a stop order to buy back a short position or sell a put option at or above the breakout price.