I am not an expert on this topic, but I'll chip-in with my observations mate.
From a price action point of view, usually I ignore these unless there is a positive reason behind it that is (semi) obvious.
For example:
STX had a huge crossing on the 17th Sep, but since then a huge crash
POS was dragged by a big seller just around the last placement/SPP (@11c) and when they sold the final lot on the 6th Aug as an off market transfer, investors took it as a buy signal and SP rallied up 30% briefly for a few days
Same happened with PGY as well recently.
Some times it could be a transfer from one account to another. If the receiving party is a custodian (e.g. CS etc that shows in the broker data) they might be borrowing it for shorting purposes.
Personally if I see a big crossing like this when the stock is a downtrend I take it as a positive signal that "good the seller is out", but if the stock is in an uptrend I am skeptical that someone took it for distribution. Obviously, I might be wrong, so please take others' inputs into consideration.
