It hasn’t been a great start to the week for Australian investors with the S&P/ASX 200 (Index: ^AXJO) (ASX:XJO) losing around 0.5% towards the back-end of today’s session.

The energy and consumer discretionary sectors have been the biggest drags on the market today, although some support has come from the consumer staples and information technology sectors.

Four shares that have really taken a beating today, include:

Crown Resorts Ltd (ASX: CWN)

Shares of Crown have crashed by as much as 12.5% today after it was revealed that 18 of the company’s employees, including at least one senior executive, have been detained by Chinese authorities. The exact charges facing the employees are unclear at this stage, although the Chinese government has carried out a number of similar raids recently in a bid to crackdown on casino-related corruption. Other shares in the sector including Star Entertainment Group Ltd (ASX: SGR) and SKYCITY Entertainment Group Limited-Ord (ASX: SKC) are also trading sharply lower on the news.

Webjet Limited (ASX: WEB)

Shares of Webjet have slid around 4% today, despite the absence of any news from the company. It appears some investors are locking in profits, which is unsurprising when you consider the shares have climbed around 135% over the past 12 months. The strong rise in the share price has really come off the back of a number of savvy overseas acquisitions combined with an impressive level of organic growth. Interestingly, Webjet has now outperformed Flight Centre Travel Group Ltd (ASX: FLT) by around 320% over the past five years (excluding dividends).

TPG Telecom Ltd (ASX: TPM)

Shares of TPG have continued to head south today, with another 3% fall to $7.53. The shares have now lost around 37% of their value since the telecommunications company provided weaker-than-expected FY17 guidance. The disappointing guidance has also drawn investors attention to TPG’s longer term growth prospects, with some fearing the NBN will severely crimp its margins. With so much uncertainty still surrounding the stock, there is a good chance the shares could continue to trade lower from here. TPG is also trading ex-dividend today, which explains a large part of the price falls.

MMA Offshore Ltd (ASX: MRM)

Shares of MMA Offshore (formerly Mermaid Marine) have fallen 5% today after the company provided another disappointing trading update. The marine services provider continues to face challenging conditions as a result of the depressed oil and gas market and now expects full year operating EBITDA will be in the order of approximately $20 million to $25 million. Although the remainder of FY17 is expected to remain challenging, MMA Offshore expects to see an improvement in vessel utilisation rates from FY18 as offshore drilling and construction activity starts to increase.

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Motley Fool contributor Christopher Georges owns shares of TPG Telecom Limited. 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.