Even after rising 16% this past week, Prothena (NASDAQ:PRTA) shareholders are still down 67% over the past three years

It's nice to see the Prothena Corporation plc (NASDAQ:PRTA) share price up 16% in a week. But that is small recompense for the exasperating returns over three years. Tragically, the share price declined 67% in that time. So the improvement may be a real relief to some. After all, could be that the fall was overdone.

The recent uptick of 16% could be a positive sign of things to come, so let's take a look at historical fundamentals.

See our latest analysis for Prothena

Prothena wasn't profitable in the last twelve months, it is unlikely we'll see a strong correlation between its share price and its earnings per share (EPS). Arguably revenue is our next best option. Generally speaking, companies without profits are expected to grow revenue every year, and at a good clip. That's because it's hard to be confident a company will be sustainable if revenue growth is negligible, and it never makes a profit.

Over the last three years, Prothena's revenue dropped 12% per year. That's not what investors generally want to see. With revenue in decline, and profit but a dream, we can understand why the share price has been declining at 19% per year. Of course, it's the future that will determine whether today's price is a good one. We'd be pretty wary of this one until it makes a profit, because we don't specialize in finding turnaround situations.

The image below shows how earnings and revenue have tracked over time (if you click on the image you can see greater detail).

If you are thinking of buying or selling Prothena stock, you should check out this FREE detailed report on its balance sheet.

A Different Perspective

Prothena shareholders are down 57% for the year, but the market itself is up 24%. Even the share prices of good stocks drop sometimes, but we want to see improvements in the fundamental metrics of a business, before getting too interested. Regrettably, last year's performance caps off a bad run, with the shareholders facing a total loss of 0.8% per year over five years. We realise that Baron Rothschild has said investors should "buy when there is blood on the streets", but we caution that investors should first be sure they are buying a high quality business. 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. For instance, we've identified 2 warning signs for Prothena that you should be aware of.

For those who like to find winning investments this free list of undervalued 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 American exchanges.

Have feedback on this article? Concerned about the content? Get in touch with us directly. Alternatively, email editorial-team (at) simplywallst.com.

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.