Right now, Gilead Sciences Inc. GILD share price is at $66.75, after a 0.45% decrease. Over the past month, the stock increased by 0.60%, but over the past year, it actually decreased by 11.58%. With questionable short-term performance like this, and great long-term performance, long-term shareholders might want to start looking into the company's price-to-earnings ratio.

The stock is currently higher its 52 week low by 18.02%. Assuming that all other factors are held constant, this could present itself as an opportunity for investors trying to diversify their portfolio with Biotechnology stocks, and capitalize on the lower share price observed over the year.

The P/E ratio is used by long-term shareholders to assess the company's market performance against aggregate market data, historical earnings, and the industry at large. A lower P/E can either represent a company's poor future earnings potential or a buying opportunity relative to other stocks. It shows that shareholders are less than willing to pay a high share price, because they do not expect the company to exhibit growth, in terms of future earnings.

Depending on the particular phase of a business cycle, some industries will perform better than others.

Gilead Sciences Inc. has a better P/E ratio of 268.2 than the aggregate P/E ratio of 42.69 of the Biotechnology industry. Ideally, one might believe that Gilead Sciences Inc. might perform better in the future than it's industry group, but it's probable that the stock is overvalued.

There are many limitations to price to earnings ratio. It is sometimes difficult to determine the nature of the earnings makeup of a company. Shareholders might not get what they're looking for, from trailing earnings.