April 19, 2010
I have noticed that when I buy at a limit price the stock seems to trade for a long time appearently at my price then I may miss the order. Sometimes I get a buy at a price and suddenly the stock price drops substantially. This effect could be explained by a trading program stepping in front of a market order, selling short to me and many waiting offers, then covering at a much lower price. This hurts me the buyer (as the stock price drops unnaturally after my buy) as well as the seller who is robbed of the best price.