First-stage base, late-stage base — what’s the difference? In CAN SLIM investing, when a stock stages an initial breakout, then climbs at least 20% from that base’s buy point to where it begins its next base, it has moved from a first- to a second-stage base. A rise of less than 20% means the next base is still a first-stage structure. The same principles hold true for second- and third-stage bases.