Moscow's arbitration court seized assets of property developer О1 Properties, owned by entrepreneur Boris Mints as part of the cleaning up of ailing lender  Financial Corporation Otkritie, Vedomosti reported on November 15.

Otkritie is questioning some of the deals struck between the lender and O1, including acquisition of O1 bonds by O1 and premature termination of contracts for loans released to the property developer.

The lender is accusing O1 of "unauthorized activities", which allegedly brought the lender losses of over RUB30bn ($501mn), although the specifics have not been disclosed.

Otkritie went bust in late August, followed by another lender, Binbank, in early September.

The Central Bank of Russia (CBR) is bailing out the two lenders and has provided a RUB380bn bailout loan to Otkritie.

The collapse of Otkritie is the third most expensive collapse of a Russian bank in modern history, after state-owned development bank Vnesheconombank (VEB) needed a $16bn bailout in 2016, and the Bank of Moscow that had a $9bn hole in its balance sheet and was taken over by the state-owned VTB group in 2011. In fourth place was the collapse of Vneshprombank, which folded late in 2015, with a RUB215.9bn ($3.6bn at average 2015 exchange rates) hole in its balance sheet.

Earlier in October, the CBR and the temporary administration of Otkritie called on customers to reopen their deposit accounts at the bank, which some industry players claimed was unfair competition.

Both Otkritie and Binbank belong to the so-called Garden Ring banks, the leading commercial banks that have been included on the CBR’s “strategically important banks” list. They have all come under increased pressure since the spring as the CBR tightened its supervision of the sector. Problems first surfaced in June when Russia’s new domestic ratings agency Analytical Credit Rating Agency (ACRA) downgraded Otkritie to BBB, which precluded it from holding state money, like pension funds.

In September, O1 Properties was reportedly in talks to sell a "significant stake" to Chinese investor.