Hello, I got a really odd fill today on an ag calendar spread. The instrument is not important, the matching algo is always the same( K, split FIFO/pro rata with TOP and LMM ).I wonder if it can be busted or adjusted. Perhaps someone has an explanation. I submitted a Buy limit order for 9 lots one tick above bid and got filled four seconds later 12 ticks UNDER my limit price(???). Moreover, the fill was 9 times 1 lots on the same second. The print appears on charts and of course I made a nice little profit( not too hard...LOL ). At first I thought it was that my platform was frozen/lagging and that I had really removed the ask that was effectively 12 ticks lower, but no. I open RAN order and my order was indeed submitted 4 seconds before the fill( and it wouldn't have printed 9*1 lots). In my mind, it was impossible to get better than your resting limit price on Globex, except perhaps when spreads have reduced ticks but it wasn't the case here... Any idea about what happened? It's the first time I see this. Thanks.