# tick data: does this data look wrong? what am I missing?

I can't seem to understand how tick data works. Below is some tick data for a certain security (I got this data from a platform called MetaTrader). At 09:56:28 someone offered to sell at \$9.9. But then at 09:57:40 someone offered to buy at \$12.89. Isn't that weird? If someone is selling at \$9.9 why would you offer to buy at \$12.89?

To make it weirder, at 09:57:30 the offer to sell at \$9.9 is repeated (or maybe it's someone else's offer?) even though someone was willing to buy at \$12.89. The entire dataset is like this.

Also: when people talk about the bid-ask spread do they mean that the bid and ask prices are horizontally aligned? Like at 10:06:00, when there is a bid price of \$11.27 and an ask price of \$11.28? What would the bid-ask spread be at, say, 09:59:23, when there was an ask price (\\$9.43) but no bid price?

• What do the Flags mean. Maybe they would shed some light (especially 4 and 2). May 2 at 0:40
• Good question. I don't, I googled around but couldn't find an answer. May 2 at 16:06
• There is no manual for the platform? If not, how can anyone use that tool? Just looking at a screenshot, without knowing the underlying is pure guessing. May 2 at 20:22
• There is a comprehensive manual, but somehow it doesn't mention the flags at all. I just found some forum discussions and it looks like the flags convey information like "tick is a result of a buy deal", "tick is a result of a sell deal", etc. But I haven't found anywhere the full INT->information correspondence. May 3 at 16:05