在交易股票的時候，投資者通常會使用扭曲的邏輯：
哪類股票價格上升後必然下降？
那些價格上升幅度陡峭，並創出新高的股票通常被認為是價格過高。有時它們的卻如此，但你也經常會發現例外：股價上漲了500%或1000%。股價上升後下跌的可能性比那些下跌之後反彈的可能性要小得多。
哪些股票價格下降後必然反彈？
價格迅速下降，創出新高的股票被認為“便宜”同時也顯示出了股票的真正價值。有時是這樣的，但是有很多股票下降後便不再回升，市場有句名言：死貓不反彈！也就是通常所說的抄底。尋找被低估的股票是市場專業人士的任務：它需要大量的研究和專業知識。
整體下降
一個相關的策略是，當價格低於之前買入價格時，買入更多的股票：如果之前的高價都樂意買入，那麼，目前的低價就算是撿著便宜了。然而接下來通常是股價繼續下跌…直至從雷達屏幕上消失。沒有人比傑西•利弗莫爾理解得更透徹，他在埃德溫•勒菲弗的《股票作手回憶錄》一書中說道：讓他先買入目標股票數量的1/5，如果這沒有給他帶來利潤，那麼他就不應該增加持有量。因為一開始他就很明顯的錯了：錯誤的情況下不可能盈利。
建議和傳聞
股票市場上的建議總體帶來的結果較差。投資者通常對所持有的股票情有獨鐘，以至於不能對它們的前景做出客觀預期。他們認為所持有股價將上升更多情況下是出於希望而不是事實。
策略建議
利用股票屏幕：
• 搜索那些價格創新高的股票；
• 根據過去12個月的相對性能研究將它們排序。選擇表現最好的10只股票做深入研究。
新高
利用價格比率指標繪出股票近3年來的相對性能。該指標應該高於0，並且仍然在升高。
好轉
它們是從遊泳池底部逐漸浮出水面的遊泳者。它們大多因失去了方向而失寵。
• 尋找新的管理模式或重大的重組，近來一兩個季度的盈利迅速增長。
• 比較預期盈利和目前的價格收益率：預期收益應該比預期盈利高。
• 利用價格比率指標繪出股票近3年來的相對性能，價格比率指標應該為正值並不斷升高。然後，等待突破信號。
總體上升而不是下降
在初次購買盈利之後，增加購買量。
行情不會說謊
不要將註意力集中在建議或謠言上。同樣的，每日新聞或者電視媒體似乎都是根據小時圖在預測市場走勢。避免信息超負荷，只有市場才是值得信任的：市場上股票價格的變動真實的顯示了正在發生的事情。專註於你所交易的框架，不要試圖去抓住短期價格波動。
Investor's Logic
Investors often use distorted logic when buying stocks:
What goes up must come down?
Stocks that rise steeply in price and make new highs are viewed as expensive and overpriced. Sometimes they are, but you will also find the real winners here - stocks that rise 500 or 1000 per cent. What goes up is more likely to be a winner than stocks that are going down!
What goes down must come back?
Stocks that fall steeply in price, making new lows, are seen as being cheap and showing real value. Sometimes they are, but many stocks never recover. The market has a saying:
Dead cats don't bounce!
Commonly referred to as bottom-fishing, searching for undervalued stocks should be left to the experts: it requires a lot of research and expertise.
Averaging down
A related strategy is to buy more of a stock if the price falls after your initial purchase: if it was a good buy at the higher price it must be a real bargain now. What often follows is that the stock keeps falling ...... disappearing from the radar screens.
No-one has put it better than Jesse Livermore in Edwin Lefevre's book Reminiscences of a Stock Operator
Let him buy one-fifth of his full line. If that does not show him a profit he must not increase his holdings because he has obviously begun wrong; he is wrong temporarily and there is no profit in being wrong at any time.
Tips and Rumors
The quality of stock market tips is generally poor. Investors often become emotionally attached to the stocks that they hold and are not always objective about their prospects. They talk their stocks up, more out of hope than conviction.
Suggested Strategies
Use Stock Screens:
• Search for stocks making New Highs; or
• Rank stocks using Relative Performance over the last 12 months. Select the top 10 per cent for further study.
New Highs
Chart the relative performance of the stock over 3 years, using the Price Ratio indicator. The indicator should be well above zero and still rising.
Turnarounds
These are bottom-swimmers that have started to rise to the surface. Often they are previous darlings of the market that have lost direction and fallen from favor.
• Look for new management, or a major restructuring, and one or two quarters of exceptionally strong earnings growth.
• Compare earnings forecasts to the current Price/Earnings ratio: expected growth must be comfortably higher than the P/E ratio.
• Chart the relative performance of the stock over 3 years, using the Price Ratio indicator. The indicator should have returned to above zero and be rising steeply.
Then wait for a breakout signal.
Average up - not down
After your initial purchase, only buy more of a stock if your existing holding shows a profit.
The tape never lies
Pay scant attention to tips or rumors. Likewise to the daily press and television media who seem to call the direction of the market on an hourly basis. Avoid the information overload and place your trust in the tape: actual price movements are the most objective information on what is actually happening in the market.
Focus on the time frame that you are trading and avoid trying to catch the short-term fluctuations.
本文翻譯由兄弟財經提供
文章來源：http://www.incrediblecharts.com/trading/investors_logic.php