These were the worst performing shares on the ASX 200 in May

The Costa Group Holdings Ltd (ASX:CGC) share price and the Mayne Pharma Group Ltd (ASX:MYX) share price were amongst the worst performers on the ASX 200 index in May. Here's why…

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Despite a disappointing end to the month, the S&P/ASX 200 index recorded a solid 1% gain in May thanks to the positive reaction to the shock election result.

Not all shares were able to charge higher with the rest of the market, though.

The four shares listed below were the worst performers on the index in May. Here's why they sank lower:

The Costa Group Holdings Ltd (ASX: CGC) share price was the worst performer on the ASX 200 in May with a disappointing 31% decline. The majority of this decline came at the end of the month when the horticulture company revealed that things weren't going to plan with a number of its operations, leading to a downgrade to its earnings guidance. Instead of NPAT-SL growth of at least 30% in calendar year 2019, Costa now expects growth between just 0.7% and 16.6%.

The Reliance Worldwide Corporation Ltd (ASX: RWC) share price crashed 24% lower last month. Investors were quick to sell the plumbing parts company's shares after it downgraded its full year earnings guidance. This downgrade was due to weaker than expected sales across the majority of its businesses.

The Mayne Pharma Group Ltd (ASX: MYX) share price was just behind it with a decline of a touch under 24% during May. Investors hit the sell button in a panic after the pharmaceutical company released a disappointing market update which revealed that its key Generics Products division had been underperforming expectations once again. During the first four months of the second half the division has posted a 32% decline in revenue compared to the prior corresponding period.

The Link Administration Holdings Ltd (ASX: LNK) share price tumbled 22% lower during May. The entirety of this decline happened on the final day of the month when the administrations services company released a disappointing trading update. Due to a number of factors, but predominantly the negative impact of Brexit on its UK-based business, the company revealed that it expects operating NPATA of between $195 million and $205 million in FY 2019. This compares to $206.7 million in FY 2018.

James Mickleboro has no position in any of the stocks mentioned. The Motley Fool Australia's parent company Motley Fool Holdings Inc. owns shares of Link Administration Holdings Ltd and Reliance Worldwide Limited. The Motley Fool Australia owns shares of and has recommended COSTA GRP FPO. The Motley Fool Australia has recommended Link Administration Holdings Ltd and Reliance Worldwide Limited. 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 Scott Phillips.

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