In Finland:
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The Financial Supervisory Authority’s (Finanssivalvonta / Fiva) list of active short positions is updated twice a day:
In the morning after 10:00 a.m.
In the afternoon after 5:00 p.m.
Reporting delay: Investors must report changed positions to Fiva by 3:30 p.m. on the trading day following the transaction date**. This means that the data shown on the list is always at least about a day behind actual market events.
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-I have noticed that short sellers take advantage of this delay: a sudden drop happens without the shorts being visible, and the price may already recover the next day by the time the short position becomes visible to others, meaning the price movement goes in the opposite direction of what the changes in visible short positions would suggest.