If the price of a share automatically declines the same amount as the dividend on the ex-div. date why don't people short the stock right before the ex-date and then when the share price drops relative to the div. payout cover the short and make a profit. Example, shares of Company A are trading at $10.00 a share on Dec 2, Gordon Gekko decides to short the stock. On Dec 3 the stock goes ex-div. and Company A is paying a 10% div or $1.00 per share. Because of this the stock opens at $9.00 a share to reflect the dividend. Why can't GG cover the short at $9.00 and walk away with a $1.00 per share profit? Is this illegal or is there some regulation to prevent this?
When you short a stock and the stock goes ex-div. you have to pay out an amount equal to the dividend. So in your example, GG would short the stock at $10.00, buy back at $9.00 and be charged $1.00 for the dividend. Net effect $0.00.
I am relative newbie in the financial market trading and as I understand it, the response from Victor is accurate in respect of trading CFD contracts. However, there is also the option to 'trade' through a financial spread betting platform which as its name suggests is purely a bet based upon the price of the underlying stock/asset. As such, I believe that your theory to short a stock just prior to its ex-dividend date may be worth investigating further... Apart from that, it's worthwhile mentioning that financial spread betting is officially recognised by HMRC as gambling and therefore not currently [2015/16] subject to capital gains tax. This info is given in good faith and must not be relied upon when making any investment and/or trading decision(s). I hope this helps you make a fortune - if it does; then please remember me!