T-trades don't always mean dilution. When a big holder wants to sell, he calls a MM. They set a target price for the trade, which will be executed in relatively small lots (usually) throughout the session, in the hope stock price won't be seriously affected. Sometimes the trades double print; that shouldn't happen. Sometimes the MM takes his fee off the top; that is reflected in the price of the T-trade.
Except for occasional late trades that print seconds after the bell, all t-trades are executed during the session, but reported after the close.
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