Investors in Mayne Pharma Group had a tough year, with a total loss of 3.4%, against a market gain of about 15%. However, keep in mind that even the best stocks will sometimes underperform the market over a twelve month period. However, the loss over the last year isn't as bad as the 8% per annum loss investors have suffered over the last half decade. We would want clear information suggesting the company will grow, before taking the view that the share price will stabilize. 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. Take risks, for example - Mayne Pharma Group has 1 warning sign we think you should be aware of.