Ideally, your overall portfolio should beat the market average. But in any portfolio, there will be mixed results between individual 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 47% over a half decade. And it's not just long term holders hurting, because the stock is down 27% in the last year. Shareholders have had an even rougher run lately, with the share price down 24% in the last 90 days.

Since Shenzhen Neptunus Bioengineering has shed CN¥385m from its value in the past 7 days, let's see if the longer term decline has been driven by the business' economics.

While the efficient markets hypothesis continues to be taught by some, it has been proven that markets are over-reactive dynamic systems, and investors are not always rational. One way to examine how market sentiment has changed over time is to look at the interaction between a company's share price and its earnings per share (EPS).

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 graphic below depicts how EPS has changed over time (unveil the exact values by clicking on the image).

Dive deeper into Shenzhen Neptunus Bioengineering's key metrics by checking this interactive graph of Shenzhen Neptunus Bioengineering's earnings, revenue and cash flow.

A Different Perspective

While the broader market lost about 13% in the twelve months, Shenzhen Neptunus Bioengineering shareholders did even worse, losing 27%. However, it could simply be that the share price has been impacted by broader market jitters. It might be worth keeping an eye on the fundamentals, in case there's a good opportunity. Regrettably, last year's performance caps off a bad run, with the shareholders facing a total loss of 8% per year over five years. Generally speaking long term share price weakness can be a bad sign, though contrarian investors might want to research the stock in hope of a turnaround. 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. Consider risks, for instance. Every company has them, and we've spotted 2 warning signs for Shenzhen Neptunus Bioengineering you should know about.

For those who like to find winning investments this free list of growing companies with recent insider purchasing, could be just the ticket.

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.