Greetings from Brazil!
I've been trading in Betfair soccer markets for more than a year and 99% of traders here in this forum must know the answer for the main question. I'm posting two screenshots from West Ham v Man Utd playing today. The first is from Match Odds Market and the second is from Over 1.5 Goals.
My question is why they put so much money in Back colum? The same happens in Lay Colum too depending on the market.
Is this one trader, let's say with a 500k bank (They put the money e close their positions in better prices?) Or this are traders who join together to avoid the price to drift?
Or maybe this are traders from Bookies like 365/William Hill that do this to avoid people from arbing prices? The only conclusion is that maybe is a Bot right?
They have some advantage in doing this? I came from Financial Markets, but I can't get the idea behind this comparing both markets. This happens in pre-live horse markets, but everyone knows that right?

I know that this is a extremely noobie question, but knowledge is power like they say.

West Ham v Man Utd (Match Odds)
https://gyazo.com/6797d262f975a09c5996324c1e7bb8d6
West Ham v Man Utd (Over 1.5)
https://gyazo.com/70687c2afa76c1517d922d9ecaa50c33