股票投資已是臺灣民眾最方便且普遍之重要理財方式。投資大眾在做投資抉擇時， 最要留意的是股價之漲跌，以便逢低買進，逢高賣出。然而，股價之波動，是否有規則可循， 或恐只能從股市之數據去探討。本文採用不同方法(包括核函法、可變核函法與遞降最大概似) 探討臺灣金融類股從79年至84年間之股價波動之長短期變動法則，並估計個股股價波動密 度，分析個股之平均報酬率與風險，以提供投資人較佳之選股策略。 本文之研究結果可分為以下兩部分:一、就短期而言，隨著每年國內外政治、經濟之變化， 股價之波動密度並沒有固定之型態;而就長期觀之，股價波動密度呈高狹峰之對稱型態。二、 從金融類股之14檔股票分別估得股價波動之密度，顯示14種股票皆呈高狹峰之對稱型態。 最後，藉由估得股價波動之密度計算每日平均報酬率與風險，並參考每年之股利，分別提出 適合規避風險、愛好風險與長期投資之投資人之個股。

　　　　　Stock investment has been a popular, convenient, but important means of portfolio management for the public. And yet it is often twisted as being highly speculative. The empirical study done by this article covers data for Banking and Insurance during the years of 1990 to 1995. In this article we attempt to arrive at rules for short term and long term of stock fluctuation from probabilistic points of view through various methods, namely kernel method, variable kernel method and maximum penalized likelihood method. In order to deduce better investment rules for the public investors, we find the probability densities of the stock fluctuation for 14 companies. Two major findings can be derived from this research. First, the probability densities of the stock fluctuation for short term are different in the situations of politics and economics; the probability densities of the stock fluctuation for long term is symmetric with narrow high peak. Second, we find that probability densities of the stock fluctuation for 14 companies are all symmetric with narrow high peak. We also give the suggestions for the risk aversors, the risk lovers and the long-run investors based on daily average return, risk and yearly dividend.