Not a sign of anything bad. In low volume trading, MMs want to make sure they can complete the transaction before they actually execute for the client. Suppose a client is looking to sell x shares at a limit of y. MM sells short first...then buys the clients shares to cover. That way they don't get caught holding the bag so to speak. Those trades show up on those daily lists. Nothing can be read into them as far as I know, except to say trading is very thin.