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Can a trade happen “in between” the bid and ask price?
I can think of the following situations in which one could see a trade occur between the visible best bid & offer: 1) on a public exchange, people have posted hidden limit orders with either bid prices above the best visible bid or offers below the best visible offer, and incoming orders have executed against this hidden liquidity[1]; 2) some orders may have been matched in dark pools which offer "mid-point matching" where buy and sell orders are matched using the mid-point of the best available publicly posted bid and offer as the reference price, and which executed trades are then reported to the public markets; or 3) some internalising broker has traded off exchange directly with a client and is now reporting the trade to the public as is often required. Now how exactly any of the above situations indicates that a "trend is about to come to an end", I do not know. [1] Exchanges often match orders on a price/visibility/time basis, whereby the orders are prioritised by price (better prices get to trade first), then by visibility (visible orders get to trade first) then by time (first come, first serve).