股票为什么会涨跌？这个问题涉及到多个复杂的市场因素，以下是基于这个问题的解析以及英文翻译对照：

首先，股票价格的涨跌受到供求关系的影响。当股票的需求增加而供应不足时，价格上涨；相反，当股票供应过剩而需求不足时，价格下跌。这种供求关系的变化会影响投资者的行为和市场情绪，进而影响股票价格。英文翻译为: Why do stocks rise and fall? This question involves multiple complex market factors. The following are the reasons and their English translations:

Firstly, the rise and fall of stock prices are influenced by supply and demand. When the demand for stocks increases and the supply is insufficient, prices rise; conversely, when the supply of stocks exceeds demand, prices fall. Changes in this supply and demand relationship affect investors' behavior and market sentiment, which in turn affect stock prices.

其次，股票价格的涨跌还受到公司业绩的影响。公司的盈利能力、财务状况和未来发展潜力等因素都会影响投资者对公司的信心和预期，进而影响股票价格。如果公司业绩良好，投资者对其未来发展前景持乐观态度，那么股票价格就会上涨；相反，如果公司业绩不佳，投资者对其未来发展前景持悲观态度，那么股票价格就会下跌。英文翻译为: Secondly, the rise and fall of stock prices are also influenced by company performance. Factors such as a company's profitability, financial condition, and future development potential affect investors' confidence and expectations in the company, which in turn affect stock prices. If a company performs well and investors are optimistic about its future development prospects, stock prices will rise; conversely, if a company performs poorly and investors are pessimistic about its future development prospects, stock prices will fall.