As earnings season begins to wrap up there is one lesson, I believe, investors can learn a great deal from – it is far better to invest in companies that under-promise and over-deliver.

Companies that have missed market expectations by a small fraction have seen their share prices fall by 30%, 40% and even 50% – all in one day. Maybe it’s just a symptom of the volatile times we currently face, but it appears investors are happy to sell first and ask questions later.

With that in mind, here are three companies that have seen their share prices hammered since the start of 2016 that I think are worth a closer look:

1. Mantra Group Ltd (ASX: MTR) – Mantra shares are now trading below $4 a share for the first time since October of last year. Many analysts were predicting strong gains for the hotel operator during 2016 as it stood to benefit from the tourism tailwind caused by the lower Australian dollar and the influx of tourists from Asia. Instead, Mantra’s share price has fallen 22% for the year to date. Looking past the recent share price action, Mantra delivered strong first half FY16 results with revenues and underlying earnings per share increasing by 21.7% and 18.6%, respectively. The company also provided updated full year NPAT guidance of between $41.5 million to $43 million, up from its earlier guidance of $40 million -$42 million. Taking the midpoint of this guidance, Mantra shares are now trading on a price-to-earnings multiple of around 24. While this appears relatively high, Mantra is expected to benefit from the tourism boom for a number of years to come and is definitely a stock I will consider buying if the share price falls much further.

2. Cover-More Group Ltd (ASX: CVO) – The travel insurance company shares are trading near their all time low levels following the release of a surprise earnings downgrade earlier in the month. I have been a supporter of the stock in the past and I still remain bullish on its long term prospects for a number of reasons, although its short term outlook remains more challenging. While higher claim costs in the first half were obviously disappointing, Cover-More is addressing this issue by moving to a different underwriting model. Whether this works or not is yet to be seen but investors can be sure management have at least identified the issue that needs to be addressed. Importantly, revenues continued to increase at a solid pace in the first half and the company’s international expansion remains on track. While I wouldn’t rush out to buy the shares just yet, I think Cover-More is definitely worthy of a spot on investors’ watchlists.

3. Vitaco Holdings Ltd (ASX: VIT) – After enjoying a strong rise for a couple of weeks following its IPO listing in September of last year, it has been pretty much downhill for the vitamin and nutrition company. Shares of Vitaco have lost more than 30% since the start of the year and are now trading at $1.85 – well below its IPO price of $2.10. Despite the company meeting its prospectus targets and re-affirming its full year IPO forecasts, the shares were sold off heavily after it released its first half results. This was possibly a sign that investors were expecting much higher growth from the company considering the huge growth its peer Blackmores Limited (ASX: BKL) is currently generating. Interestingly, Blackmores shares have also lost around 28% this year as some investors become more concerned about the possibility of the Chinese government cracking down on foreign imports of vitamins and baby formula. Despite its recent decline, Vitaco shares are still trading at a forecast price-to-earnings multiple of around 25 – not particularly cheap especially if sentiment in the sector takes a turn for the worse. As a result, investors should be weary of further price falls and perhaps wait for the dust to settle before becoming a shareholder.

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Motley Fool contributor Christopher Georges has no position in any stocks mentioned. Unless otherwise noted, the author does not have a position in any stocks mentioned by the author in the comments below. The Motley Fool Australia has no position in any of the stocks mentioned. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy. This article contains general investment advice only (under AFSL 400691). Authorised by Bruce Jackson.