Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

Some very intelligent individuals may still argue that the markets are rational, but each and every day, we can easily find a number of stock moves that can be chalked up to irrational thinking. Sometimes, those moves are due to irrational behaviors in the past, making the current day's price change a simple correction when investors realize the previously made mistake. But other times, a stock will move dramatically lower or higher because of a small and non-materialistic change of some sort. The length and severity of these irrational moments can be days, weeks, months, or simply hours.

But noticing them, and learning from them, can help you become a better investor for a number of different reasons. First and foremost is that, when you understand and accept that these types of things happen, you'll be somewhat prepared when they occur to stocks you own. Then, hopefully, you won't fall prey to the irrational behavior, but be able to take advantage of it by purchasing shares when the market has undervalued them. These "buying opportunities" are a wonderful way to maximize your investment returns and, over time, will help your portfolio grow to its full potential.

Let's take a look at a few stocks that displayed some irrational behavior today.

Although most Foolish investors don't need to be told this again, a reminder from time to time has never hurt anyone. Foolish investors don't buy on hype, or get pulled into buying a stock the first day it goes public. Thus, todays first irrational market move was shares of Twitter (NYSE:TWTR) opening at $45.10, or up 73.46% from where it was priced last night. Not only did shares open much higher than where they were priced, but they managed to rise up to $50.09 at one point during the day, prior to closing at $44.90, which was lower than where they opened for the day. 

The insane amount of hype and excitement got the best of a number of investors today, and the sad part is that most of the fools who bought shares today got in because they thought they could get rich quickly; but, for the most part, today, they lost money. To make matters worse, it's possible that the shares will decline even further tomorrow as the hype wears off, and the reality that today's buying was irrational sets in -- and investors bail.

If you believe that Twitter is a great company and has a wonderful future ahead of itself (just like I do), the Foolish thing to do is let things calm down, allow the stock price and valuation to come back down to earth, and then buy shares in a few weeks or months from now.

The other irrational move of the day was shares of Geron Corp. (NASDAQ:GERN), a small clinical stage biopharmaceutical company that not only closed up 44.72% for the day, but rose as much as 116.38% during early hours of trading. The cause for the massive share price jump was a report released by Geron indicating that its blood disorder drug Imetelstat had produced strong clinical data results. In a study comprised of 18 individuals, 44% showed improved or partial remission, or even complete remission of Myelofibrosis, which is a disease were abnormal blood cells build up in the bone marrow and slows the production of healthy blood cells.

Furthermore, an analyst from Piper Jaffary & Co. believes this will be enough evidence so Geron can take the drug to a Phase 2 study. I must admit this is great news for those suffering from Myelofibrosis, and a sign that Geron may have a wonderful drug. But this was a Phase 1 study; the drug still needs to perform well in a Phase 2 and Phase 3. Then it needs to be reviewed by the FDA for a number of weeks, or even months. And finally, the drug needs to be prescribed to patients before Geron ever makes a dollar from this drug. This whole process, starting from today, could take years.

Investors not only acted irrational this morning by buying shares right after the news was released -- when the hype and excitement was at its highest -- but they continued to buy the stock all day long on the basis of one drug performing well in a Phase 1 study, despite the fact that hundreds of things could go wrong before Geron ever makes any money from this product. 

Irrational behavior was at its best today, my friends.

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