RE: Ignorance Question15 Jan 2020 15:41
Hi NLLeeroy, I can back up what bilbs said as I've had many of my own buys/sells marked up incorrectly, so it's obviously guessed by a computer program (and obviously not a sophisticated one). Most of the time it works ok because the trades are quite small and the transactions are quick so the traded price is compared with the current spread.
With shares like ITM, as has happened here a lot recently, it's a small market but a handful of bigger players want to buy a substantial number of shares. Although the market makers are not exactly holding these back you don't get to see them until they are fulfilled and all the while the market makers are raising the price trying to encourage holders to part with some shares. When you see this happening you often find at the end of the day the large trade will be recorded once the MMs achieved their aim of matching the big buyer with enough sellers. However the trade price is an average of all the trades that were used to fulfill it during the day and the computer program often misjudges it as a sell when in fact it was a large buy, because it compares that average price (lower earlier in the day) against the current market spread and nothing to do with the spreads of the actual trade itself. It sees the price at the lower end of the spread and marks it up incorrectly as a sell.
On a further note, I'm fairly sure the market makers don't (or at least try not to) hold back shares for themselves. They make their money on the spread (difference between buy and sell price) and just like us they have no idea what tomorrow will bring regarding buyers and sellers so they can't take the risk holding (too many) shares into a new trading day...otherwise any bad news overnight could wipe them out.