Turkey seeks arrest of 68 Bank Asya shareholders over Gulen links
The operation, focusing on Istanbul and encompassing nine provinces, targeted "class A" shareholders who had voting rights to determine the bank's administrative board, police said on Wednesday.
The state-run Anadolu news agency said 49 of the suspects had been held so far.
Bank Asya was founded by followers of the US-based cleric Fethullah Gulen, and was seized by the state in 2015 along with other Gulen-linked firms in a government crackdown.
The government of President Recep Tayyip Erdogan claims Gulen masterminded the 2016 attempted coup, in which more than 240 people, many of them unarmed civilians, were killed by rogue soldiers.
Gulen, who has lived in self-imposed exile in the United States since 1999, has denied the charges and condemned the coup and subsequent "witch hunt".
Since the failed coup, more than 50,000 people, including civil servants and security personnel, have been jailed pending trial and some 150,000 suspended or dismissed from their jobs under state of emergency rule imposed and extended by Erdogan.