This column was originally published on RealMoney on July 21 at 12:39 p.m. EDT. It's being republished as a bonus for TheStreet.com readers.It's time to talk about tops. Tops in the market, sectors, industry groups, stocks, all of 'em. As long as I've been in the trading game, I've heard lots of talk about tops. Seems like the market is always topping out. I remember hearing it from some really, really smart guys back in 1998. Those same guys were yipping about the top again in mid-1999. Ultimately, they were correct; but in the meantime, they had been run over by a herd of bulls while waiting for their positions to be vindicated. Tops are usually processes that unfold over time rather than specific events. It takes a lot of time to grind through all the hope, greed, wishful thinking and results-oriented analysis that buoys prices for longer than most folks think. I catch myself saying on a regular basis, "Always ask who is behind you when you're buying something." In other words, once you've bought, you become a cheerleader. All the hope in the world doesn't push the stock higher; it takes new buyers who are slower on the draw, but who ultimately pull the trigger. This concept of looking back before taking a position is the second most useful tool in my trading shed. You don't want to be the last bull in the herd because you'll just wind up with a mouth full of dirt. Avoid trying to anticipate a top. Some tops are pretty obvious (as in the first chart on the next page), but typically you'll just get beaten up playing the anticipation game. This is critically important for those who study charts. Charts work quite well for assessing the psychology of the crowd, and the impact of price changes on that psychology. Will a price decline flush out a bunch of sellers as the price change turns lots of winners into losers? Will an advance out of a prolonged trading range wake the sleepy crowd and attract buyers who had been invested elsewhere? Various identifiable price patterns illustrate this dynamic. But the pattern must be complete. A partial pattern is analogous to almost falling off a cliff. What could have been is not what is. When you start anticipating the completion of a reversal pattern, you are essentially flipping a coin: "Heads, the trend reverses; tails, it continues." Lately, there has been a lot of chatter about these ominous head-and-shoulder patterns that are flashing sell signals. I can't find any -- yet! I see a bunch of potential patterns, but can't find anything that has definitively fallen off a cliff. Let's look at a potential head-and-shoulder pattern in the Oil Services HOLDRs ( OIH).