As an investor, mistakes are inevitable. But really bad investments should be rare. So take a moment to sympathize with the long term shareholders of Block, Inc. (NYSE:SQ), who have seen the share price tank a massive 72% over a three year period. That'd be enough to cause even the strongest minds some disquiet. Contrary to the longer term story, the last month has been good for stockholders, with a share price gain of 8.9%. But this could be related to good market conditions, with stocks up around 3.9% during the period.

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

See our latest analysis for Block

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. By comparing earnings per share (EPS) and share price changes over time, we can get a feel for how investor attitudes to a company have morphed over time.

During five years of share price growth, Block moved from a loss to profitability. We would usually expect to see the share price rise as a result. So given the share price is down it's worth checking some other metrics too.

We note that, in three years, revenue has actually grown at a 13% annual rate, so that doesn't seem to be a reason to sell shares. This analysis is just perfunctory, but it might be worth researching Block more closely, as sometimes stocks fall unfairly. This could present an opportunity.

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

Block is a well known stock, with plenty of analyst coverage, suggesting some visibility into future growth. Given we have quite a good number of analyst forecasts, it might be well worth checking out this free chart depicting consensus estimates.

A Different Perspective

It's good to see that Block has rewarded shareholders with a total shareholder return of 61% in the last twelve months. That's better than the annualised return of 3% over half a decade, implying that the company is doing better recently. In the best case scenario, this may hint at some real business momentum, implying that now could be a great time to delve deeper. 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. Case in point: We've spotted 1 warning sign for Block you should be aware of.