In afternoon trade the S&P/ASX 200 (Index: ^AXJO) (ASX: XJO) is up 0.1% to 5,845 points after giving back its strong early gains.
Four shares which have acted as a drag on the market today are listed below. Here's why they have been crushed:
The National Australia Bank Ltd, (ASX: NAB) share price has tumbled 3.5% to $31.45 today. The majority of today's decline can be attributed to its shares going ex-dividend. NAB's interim dividend is a fully franked 99 cents and will be paid on July 5.
The Sirtex Medical Limited (ASX: SRX) share price has fallen 4% to $14.83 despite there being no news out of the biotechnology company. Following today's decline, the Sirtex share price has now fallen a massive 52% in the last 12 months.
The Vita Group Limited (ASX: VTG) share price has continued its decline, this time by 6% to $1.29. Incredibly, the shares of the operator of Telstra Corporation Ltd (ASX: TLS) retail stores have now lost 39% of their value in just the last five trading days. Concerns over its ongoing negotiations with the telco giant are behind this latest decline.
The Vocus Group Ltd (ASX: VOC) share price has dropped almost 4% to $2.35. This latest decline means the fast-growing telco giant's shares have now fallen 73% in the last 12 months. Whilst I think the company could have a bright future, with short interest continuing to rise, I would suggest investors hold off an investment until its full-year results have been announced.