許多提供投資建議的書籍都指出投資者心理在建立和維護一個大型投資組合時起著非常重要的作用。投資者需要了解他們的個性特點和這些個性是怎樣影響他們做決定的過程的。成功的投資者利用積極的個性特點做出有利的投資決定，消極態度則會引起糟糕的投資決定。一個關於何時賣出一支股票的糟糕決定可以引起重大損失。
一些壞習慣可能導致購買股票的決定有缺陷，而另一些壞習慣則會導致賣出或者繼續持有的錯誤決定。許多買入錯誤源於沒有充分調查的倉促決定和對風險偏好控制的失敗。導致賣出錯誤的壞習慣有很多，而且更難控制。投資者的心理可能裝滿地雷，將會破壞在其他成功投資組合管理上的努力。
過度自信
過度自信與偏見將會一起放大無紀律投資者的錯誤。在特定股票獲得巨大利潤後，這些投資者可能會理所當然地認為價格會繼續上漲，而不會考慮導致價格上漲的特定因素和環境。當投資者認為他們選擇股票的能力是這些巨大獲利的原因時，過度自信將會影響決定做出過程。類似的，投資者也可能僅僅因為好運氣而變得過度自信。這種態度可能導致損失的出現，從而抹除之前所有的獲利。
投資者確認偏差的另一個問題可能發生在失敗的投資之後。盡管所選擇股票的價格在持續下跌，投資者則繼續尋找能證實其投資實際上是錯誤決定的文章或者新聞報道。一些人持續失敗是因為相信對一支股票會成為下一只蘋果股票的反複聲明，這是帶有確認偏見的執念。
設定一個目標
明智的投資者通常是有計劃地開始交易。在購買股票之前，他們會設定一個目標或者出售的目標價位，當股票達到目標價位後就會出售。這一方法在投資者處於短期機會時非常有用。
當賣方分析師在做股票建議時提供目標價位，投資者應該全面調查並確定這些分析師的每股收益預測是否合理。分析師在進行收益預測和建立估值指標時會使用合理的假設，例如股價的市盈率和買價與賣家的比率。如果聽從分析師的價格目標建議，及時根據股票發售公司的網站頁面信息做出目標價格修改非常重要。這些信息對股票價格有巨大影響。
使用技術分析是建立目標價格的另一個流行方法。許多投資者通過研究股票價格圖表、尋找竭盡缺口出現的信號來做決定，這些信號表明股票正在試圖通過交易量激增來達到一個新的價格高度。
一個建立股票目標價格的流行方法是使用斐波納奇回調線在股票價格在長趨勢中短期變化時預測抗升水平。有時明顯的回調就是反彈的開始，將會改變長期趨勢。
使用這些工具將是一個複雜的過程，將會證明賣出決定比買入決定要困難的多。賣出股票需要建立目標價格和保持自律。
遵守計劃
在股票價格上漲到出售價格區間的時候投資者都會受到貪婪的誘惑。這是投資者必須要保持自律避免過火的另一個區域，因為股票價格可能從目標價格處下跌。許多投資者使用逐步出售的方法，而不是一下子全賣出。這一方法是在一個目標價位賣出一部分，例如三分之一或者二分之一，保留進一步盈利的機會並防止錯失原來的巨大盈利。
4 Reasons Why Selling Is Harder Than Buying
Many books offering investing advice discuss how investor psychology plays a key role in determining an individual’s success in building and maintaining a strong portfolio. Investors need to be aware of their own personality traits and how those qualities could affect their decision-making process. Successful investors take advantage of their positive traits that lead to advantageous investing decisions, and either control or eliminate negative attitudes that cause bad investment decisions. A bad decision about when to sell a stock can cause a significant loss.
Bad Habits and Big Mistakes
While some bad habits can lead to flawed decisions about buying stocks, other bad habits lead to mistakes in selling or not selling investments. Many buying mistakes result from hasty decisions without adequate research and the failure to control one's risk appetite. Bad habits that cause selling mistakes are numerous and more difficult to control. An investor’s psychology can be loaded with land mines, potentially undermining otherwise diligent efforts at successful portfolio management.
Overconfidence
Overconfidence can combine with outcome bias to intensify the mistakes of an undisciplined investor. After booking impressive gains on a particular stock, such an investor might assume the price would continue to climb, without considering the particular factors and circumstances that caused the stock or ETF to begin its advance. Overconfidence has an impact on the outcome-biased decision-making process when the investor believes his own unique stock-picking abilities are responsible for those big gains. Similarly, investors can become overconfident simply because they are experiencing a run of good luck. Such attitudes can bring about an unlucky phase, erasing the previously accumulated profits.
Another problem for investors arises from confirmation bias, which can occur after an individual makes a bad investment. Despite a steadily declining price for the selected stock, the investor continues to search for articles or news reports appearing to validate what was actually a bad decision. Someone who insists on staying with a loser because of a repeated claim that the stock could become the next Apple Inc. (NASDAQ: AAPL) is supporting that unfounded belief with confirmation bias.
Set a Target
Smart investors usually enter a trade with a plan. Before buying shares, they establish a goal or target price at which they plan to sell. Many traders place a limit order immediately after purchasing shares, which triggers a sale when the stock reaches the specified price. This practice is particularly useful in situations when the trader is otherwise occupied during what might be a brief window of opportunity.
When sell-side analysts provide target prices while making stock recommendations, the investor should use due diligence and determine whether the analyst based the opinion on reasonable earnings per share (EPS) forecasts. Analysts should use reasonable assumptions in making earnings forecasts and in establishing valuation metrics, such as the price-to-earnings (P/E) ratio and the price-to-sales (P/S) ratio. When following analysts’ price targets, it is important to stay current with any revisions to those targets by regularly checking the investor information page at the website of the company issuing the shares. Such information can drastically impact a stock price. A number of commercial websites offer stock price targets for a fee, such as ExitPoint.com and Briefing.com.
Use of technical analysis is another popular means of establishing target prices. Many investors make a practice of playing the gap by studying stock price charts and looking for such signals as an exhaustion gap, indicating a stock’s final attempt to reach a new high with an abrupt surge on high trading volume.
A popular method for establishing a target price involves the use of Fibonacci retracement to forecast resistance levels when the stock price makes short-term changes against the longer-term trend. Sometimes an apparent retracement is the beginning of a reversal, changing the longer-term trend.
The use of these tools can become a complicated process, demonstrating how it is more difficult to make a selling decision than a buying decision. Selling stocks involves establishing target prices and maintaining self-discipline.
Staying With the Plan
There is often a temptation to get greedy as a stock price climbs toward the selling target range. This is another area where the investor must maintain self-discipline to avoid overshooting because the stock price might decline from the target level. Many traders follow a strategy of phasing out of a position rather than selling all shares at once. This approach involves selling a fraction, such as one-half or one-third of the shares, at a time, preserving the opportunity for further gains while avoiding the mistake of missing a significant profit.
本文翻譯由兄弟財經提供
文章來源：http://www.investopedia.com/articles/markets/052416/4-reasons-why-selling-harder-buying.asp