I cannot believe the amount of discussion re: 18 share trade.  I have done this many times in the past and there is nothing sinister about it.  If I decide to sell a position that has say 618 shares, the 600 will be sold at market as it constitutes  even numbers (board lots). The 18 will be sold at the next lower level that has an uneven number of shares available. sometimes it is only a penny, sometimes as much as .10 lower.

K