In order to justify the effort of selecting individual stocks, it's worth striving to beat the returns from a market index fund. But every investor is virtually certain to have both over-performing and under-performing stocks. So we wouldn't blame long term Shenzhen Neptunus Bioengineering Co., Ltd. (SZSE:000078) shareholders for doubting their decision to hold, with the stock down 42% over a half decade. But it's up 5.3% in the last week. Less than a week ago Shenzhen Neptunus Bioengineering announced its financial results; you can catch up on the most recent data by reading our company report.

Although the past week has been more reassuring for shareholders, they're still in the red over the last five years, so let's see if the underlying business has been responsible for the decline.

View our latest analysis for Shenzhen Neptunus Bioengineering

In his essay The Superinvestors of Graham-and-Doddsville Warren Buffett described how share prices do not always rationally reflect the value of a business. One imperfect but simple way to consider how the market perception of a company has shifted is to compare the change in the earnings per share (EPS) with the share price movement.

In the last half decade Shenzhen Neptunus Bioengineering saw its share price fall as its EPS declined below zero. Since the company has fallen to a loss making position, it's hard to compare the change in EPS with the share price change. However, we can say we'd expect to see a falling share price in this scenario.

The image below shows how EPS has tracked over time (if you click on the image you can see greater detail).

Before buying or selling a stock, we always recommend a close examination of historic growth trends, available here.

A Different Perspective

Shenzhen Neptunus Bioengineering shareholders gained a total return of 5.0% during the year. But that return falls short of the market. On the bright side, that's still a gain, and it is certainly better than the yearly loss of about 7% endured over half a decade. It could well be that the business is stabilizing. I find it very interesting to look at share price over the long term as a proxy for business performance. But to truly gain insight, we need to consider other information, too. Even so, be aware that Shenzhen Neptunus Bioengineering is showing 2 warning signs in our investment analysis , you should know about...

If you like to buy stocks alongside management, then you might just love this free list of companies. (Hint: insiders have been buying them).

Please note, the market returns quoted in this article reflect the market weighted average returns of stocks that currently trade on Chinese exchanges.

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This article by Simply Wall St is general in nature. We provide commentary based on historical data and analyst forecasts only using an unbiased methodology and our articles are not intended to be financial advice. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. We aim to bring you long-term focused analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material. Simply Wall St has no position in any stocks mentioned.