If we were to recollect the basic theory followed in markets, the Dow Theory, then, new highs are telling us that the economy is healthy and that is the reason why the Indices, which represent the top stocks is making new highs. The dow theory believes that all information - past, current and even future - is discounted into the markets and reflected in the prices of stocks and indexes.
That information includes everything from the emotions of investors to inflation and interest-rate data, along with pending earnings announcements to be made by companies after the close. Based on this tenet, the only information excluded is that which is unknown, such as a massive earthquake. But even then the risks of such an event are priced into the market.
It's important to note that this is not to suggest that market participants, or even the market itself, are all knowing, with the ability to predict future events. Rather, it means that over any period of time, all factors - those that have happened, are expected to happen and could happen - are priced into the market. As things change, such as market risks, the market adjusts along with the prices, reflecting that new information.
The other important Dow theory tenet applicable to this situation would be , The Trend Remains In Effect Until Clear Reversal Occurs. This is a very important tenet to be remembered especially by those who have the habit to 'Jump the gun' in the greed to short at the top.
The reason for identifying a trend is to determine the overall direction of the market so that trades can be made with the trends and not against them. A trend remains in effect until the weight of evidence suggests that it has been reversed. Traders should wait for a clear picture of a trend reversal because the goal is not to confuse a true reversal in the primary trend with a secondary trend or brief correction. Remember that a secondary trend is a move in the opposite direction of the primary trend that will not continue. For example, imagine that the primary trend is up, but the indexes are currently selling off. If an investor were to take a short position, concluding that the sell-off is the start of a new primary downward trend, they could get burned when the primary trend resumes.
Unless you can safely conclude, based on the weight of evidence, that the trend has changed, you will be trading against the trend. As a general rule, this is not a wise idea, as many have been hurt by trading against the market.
Coming back to the question -- should you trade a stock/index which is making new highs? The fact is that there is nearly always a fundamental reason why prices are making new highs. It is a clear sign of a successful company / index that is performing well at the moment.
Look at historical charts and you will observe that many of these breakouts last several days, weeks or even months. So you can profit from these breakouts whether you are a long-term investor or a short-term trader.The fact is that many fund managers, hedge funds and private investors are all keeping on eye on stocks that are making new highs. Therefore as soon as they spot a decent company whose shares are making new highs, many of them will start buying or trading their shares so they can ride this breakout. As a result of this you obviously get a lot of momentum behind this breakout and therefore the price just keeps on going higher. Of course not every breakout is successful because some breakouts run out of momentum very quickly, but a lot of breakouts will result in big price moves to the upside.
What if this is the last few points up with a reversal lurking inconspicuously ? At such levels, it's a really tough and volatile market though. There are so many bullish and bearish arguments, trying to decipher which ones make the most sense is next to impossible. But always keep one thing in mind: The market uses every bit of known information to come up with current prices. Don't believe for a minute that you have knowledge that the market hasn't considered. There's a reason it's priced where it is. So always leave the door open on both sides - bullish and bearish.


