An upside breakout occurs when the price of a security decisively moves above a well-established resistance level—such as a horizontal price ceiling, a trendline, or the upper boundary of a chart pattern like a triangle or rectangle—typically on strong volume. Technical traders view a confirmed upside breakout as a bullish signal indicating that buying demand has overpowered supply at a key level, and that prices may continue to rise. Successful upside breakouts are often accompanied by increased volume (confirming genuine buying conviction), a retest of the breakout level as new support, and follow-through price appreciation in subsequent sessions.