许多提供投资建议的书籍都指出投资者心理在建立和维护一个大型投资组合时起着非常重要的作用。投资者需要了解他们的个性特点和这些个性是怎样影响他们做决定的过程的。成功的投资者利用积极的个性特点做出有利的投资决定，消极态度则会引起糟糕的投资决定。一个关于何时卖出一支股票的糟糕决定可以引起重大损失。
一些坏习惯可能导致购买股票的决定有缺陷，而另一些坏习惯则会导致卖出或者继续持有的错误决定。许多买入错误源于没有充分调查的仓促决定和对风险偏好控制的失败。导致卖出错误的坏习惯有很多，而且更难控制。投资者的心理可能装满地雷，将会破坏在其他成功投资组合管理上的努力。
过度自信
过度自信与偏见将会一起放大无纪律投资者的错误。在特定股票获得巨大利润后，这些投资者可能会理所当然地认为价格会继续上涨，而不会考虑导致价格上涨的特定因素和环境。当投资者认为他们选择股票的能力是这些巨大获利的原因时，过度自信将会影响决定做出过程。类似的，投资者也可能仅仅因为好运气而变得过度自信。这种态度可能导致损失的出现，从而抹除之前所有的获利。
投资者确认偏差的另一个问题可能发生在失败的投资之后。尽管所选择股票的价格在持续下跌，投资者则继续寻找能证实其投资实际上是错误决定的文章或者新闻报道。一些人持续失败是因为相信对一支股票会成为下一只苹果股票的反复声明，这是带有确认偏见的执念。
设定一个目标
明智的投资者通常是有计划地开始交易。在购买股票之前，他们会设定一个目标或者出售的目标价位，当股票达到目标价位后就会出售。这一方法在投资者处于短期机会时非常有用。
当卖方分析师在做股票建议时提供目标价位，投资者应该全面调查并确定这些分析师的每股收益预测是否合理。分析师在进行收益预测和建立估值指标时会使用合理的假设，例如股价的市盈率和买价与卖家的比率。如果听从分析师的价格目标建议，及时根据股票发售公司的网站页面信息做出目标价格修改非常重要。这些信息对股票价格有巨大影响。
使用技术分析是建立目标价格的另一个流行方法。许多投资者通过研究股票价格图表、寻找竭尽缺口出现的信号来做决定，这些信号表明股票正在试图通过交易量激增来达到一个新的价格高度。
一个建立股票目标价格的流行方法是使用斐波纳奇回调线在股票价格在长趋势中短期变化时预测抗升水平。有时明显的回调就是反弹的开始，将会改变长期趋势。
使用这些工具将是一个复杂的过程，将会证明卖出决定比买入决定要困难的多。卖出股票需要建立目标价格和保持自律。
遵守计划
在股票价格上涨到出售价格区间的时候投资者都会受到贪婪的诱惑。这是投资者必须要保持自律避免过火的另一个区域，因为股票价格可能从目标价格处下跌。许多投资者使用逐步出售的方法，而不是一下子全卖出。这一方法是在一个目标价位卖出一部分，例如三分之一或者二分之一，保留进一步盈利的机会并防止错失原来的巨大盈利。
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.
本文翻译由兄弟财经提供
文章来源：http://www.investopedia.com/articles/markets/052416/4-reasons-why-selling-harder-buying.asp