Amid sharp, mostly downward volatility in crypto markets, BlockFills has halted withdrawals and restricted trading on its platform, a person familiar with the matter told CoinDesk.

Clients were informed of the decision by internal email, according to TheMinerMag.

Based in Chicago and backed in part by market-making giant Susquehanna Investment Group, BlockFills saw $60 billion in trading volume last year, according to the Financial Times.

"In light of recent market and financial conditions, and to further the protection of clients and the firm, BlockFills took the action last week of temporarily suspending client deposits and withdrawals," a spokesperson told the newspaper.

"Clients have been able to continue trading with BlockFills for the purpose of opening and closing positions in spot and derivatives trading and select other circumstances," the spokesperson said.

BlockFills' moves come as the months-long slide in crypto prices accelerated into a full-blown crash last week. Bitcoin BTC$67,427.03 plunged to as low as $60,000 before bouncing to its current $67,000, still down about 50% from its record high last October.

The action is reminiscent of 2022’s crypto winter, which saw numerous platforms forced to suspend withdrawals as the bear market deepened, with many of them ultimately collapsing.

UPDATE (Feb. 12, 09:44 UTC): Changes sourcing in first paragraph to a person familiar.