Right now, Amgen Inc. AMGN share price is at $229.33, after a 0.45% drop. Over the past month, the stock went up by 7.29%, but over the past year, it actually decreased by 3.54%. 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 above its 52 week low by 15.45%. 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 measures the current share price to the company's EPS. It is used by long-term investors to analyze the company's current performance against its past earnings, historical data and aggregate market data for the industry or the indices, such as S&P 500. A higher P/E indicates that investors expect the company to perform better in the future, and the stock is probably overvalued, but not necessarily. It also shows that investors are willing to pay a higher share price currently, because they expect the company to perform better in the upcoming quarters. This leads investors to also remain optimistic about rising dividends in the future.

Most often, an industry will prevail in a particular phase of a business cycle, than other industries.

Compared to the aggregate P/E ratio of the 94.38 in the Biotechnology industry, Amgen Inc. has a lower P/E ratio of 23.75. Shareholders might be inclined to think that the stock might perform worse than its industry peers. It's also possible that the stock is undervalued.

P/E ratio is not always a great indicator of the company's performance. Depending on the earnings makeup of a company, investors can become unable to attain key insights from trailing earnings.