Jackroch, I assume that it represents trades among MMs who are settling up accounts for the day. Generally happens when there is fast trading and things get out of kilter. That is not the case here as there is not that much volume. Why the t-trades are off-setting an earlier trade is a real mystery since the earlier trades have been logged and time stamped. Also, the fact that it always is the same amount is peculiar. Several weeks ago there were a number of t-trades which were discussed, but at that time they were for varying amounts.