Shareholders in Castle Biosciences (NASDAQ:CSTL) have lost 65%, as stock drops 10% this past week

Simply Wall St

We think intelligent long term investing is the way to go. But along the way some stocks are going to perform badly. For example, after five long years the Castle Biosciences, Inc. (NASDAQ:CSTL) share price is a whole 65% lower. That's not a lot of fun for true believers. And some of the more recent buyers are probably worried, too, with the stock falling 33% in the last year. More recently, the share price has dropped a further 28% in a month.

After losing 10% this past week, it's worth investigating the company's fundamentals to see what we can infer from past performance.

Castle Biosciences 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. Some companies are willing to postpone profitability to grow revenue faster, but in that case one would hope for good top-line growth to make up for the lack of earnings.

Over five years, Castle Biosciences grew its revenue at 38% per year. That's better than most loss-making companies. Unfortunately for shareholders the share price has dropped 10% per year - disappointing considering the growth. This could mean high expectations have been tempered, potentially because investors are looking to the bottom line. Given the revenue growth we'd consider the stock to be quite an interesting prospect if the company has a clear path to profitability.

The graphic below depicts how earnings and revenue have changed over time (unveil the exact values by clicking on the image).

NasdaqGM:CSTL Earnings and Revenue Growth August 4th 2025

This free interactive report on Castle Biosciences' balance sheet strength is a great place to start, if you want to investigate the stock further.

A Different Perspective

While the broader market gained around 22% in the last year, Castle Biosciences shareholders lost 33%. 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 10% 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. It's always interesting to track share price performance over the longer term. But to understand Castle Biosciences better, we need to consider many other factors. Even so, be aware that Castle Biosciences is showing 2 warning signs in our investment analysis , and 1 of those is a bit concerning...

If you like to buy stocks alongside management, then you might just love this free list of companies. (Hint: many of them are unnoticed AND have attractive valuation).

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

Valuation is complex, but we're here to simplify it.

Discover if Castle Biosciences might be undervalued or overvalued with our detailed analysis, featuring fair value estimates, potential risks, dividends, insider trades, and its financial condition.

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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.