Prime brokerage firms including GS, CITI, BoA, Jeffries are tightening risk control, imposing higher collateral requirements and straight out limiting shorting certain stocks

trying to protect themselves against costs from extreme surges and dips like those seen in AMC, MicroVision, and GameStop

"Until further notice, Jefferies Prime Brokerage will no longer offer custody on naked options" in GameStop, AMC and MicroVision, the firm said in a memo to clients seen by Bloomberg News.

Link here for more info, not gated.

Over the weekend Adam posted: Why it's best to stay away from the AMC madness

Prime brokerage firms including GS, CITI, BoA, Jeffries are tightening risk control, imposing higher collateral requirements and straight out limiting shorting certain stocks