How this works
A base is a stretch of sideways trading after a prior advance. Its buy point is the price the stock has to clear to break out of it. Where that buy point sits depends on the pattern. In a cup with handle, it's the highest point in the handle. In a flat base, it's the high on the left side. In a double bottom, it's the middle peak of the W. All three mark the same thing: an area of past resistance. A stock that clears it is signalling that a bigger move may follow.
The buy zone runs from the buy point to 5% above it. The stop-loss is measured from your entry, so the closer you buy to the buy point, the more room you have. Leading stocks often pull back to test their buy points after breaking out. If you bought at the top of the zone, that normal pullback already costs you almost 5%, leaving only about 3% before an 8% stop. If you bought right at the buy point, the same pullback costs you nothing yet. That's why the usual advice is to start the position as close to the buy point as you can, then use the rest of the 5% zone to add shares.
Volume is the confirmation. A breakout is more convincing when trading volume on that day is well above average. IBD commonly looks for at least 40-50% above the 50-day average. The BLDR example broke out on below-average volume and then chopped sideways for weeks. The entry was right at the buy point, so the September low of $50.59 was only 4.2% below it. That was never close to the 8% stop, and the stock held above its 50-day moving average. It later gapped up on earnings and peaked at $86.48, a 64% gain from the entry.
Where this is honest about its limits
This tool does the arithmetic of an entry. It can't tell you whether a pattern is valid, whether the market as a whole is in an uptrend, or whether the company's earnings justify the move. Those judgments are the harder part of CAN SLIM. Buy points, the 5% zone and the 7-8% rule are rules of thumb, not guarantees: breakouts fail often, and a stop-loss can fill well below its level if a stock gaps down overnight. The worked example is drawn from an Investor's Business Daily column. For the fundamental side of a stock decision, see the Valuation Assumption Analyst and the DCF model.