The exact same setup is shaping up in shares of car part retailer AutoZone ( AZO) right now. AutoZone is currently forming a nearly textbook descending triangle pattern of its own, with its horizontal support level right at $355. In real terms, the descending triangle is a significant pattern because it demonstrates that sellers are in control of shares. 10 Companies That Prove Stock Picking Is Still Alive While buyers have historically been willing to step in with a bid at $355, every time that stock slips down to that level, some of the glut of demand is getting absorbed by asks. When all of the buyers get taken out at $355, AZO's price is going to fall through support - when that happens, the "safety net" is gone, and downside becomes the high-probability price objective for the stock. Momentum adds some extra confirmation to this downside setup: 14-day RSI has been stuck in a downtrend since before AZO topped back in May. Because momentum is a leading indicator of price, the fact that the downtrend is still in force doesn't bode well for AZO shareholders. While the stock's most recent test of $355 held up yesterday, AZO is clearly getting close to a more significant breakdown. Watch out.