You start trading with an account worth $$500,000.$ You decide that the most you want to risk on any trade is $0\mathrm{.}50\%$ of the account value. You've been following a stock and believe the appropriate entry point is $$40$ per share with an $8\%$ trailing stop. Based on this information, how many shares do you initially buy?

$625$

$1,250$

$391$

$781$