The shares of Brentwood-based KV Pharmaceutical have risen so sharply since June 9 that the New York Stock Exchange has contacted the troubled firm about the unusual trading activity.

It’s unclear what’s causing the steep increase and the company has a policy about not commenting on unusual trading activity.

Although the company’s Class A shares rose only 14 cents to close at $3.24 on Wednesday, the share price has nearly doubled from its June 9 close of $1.68. The increase in the Class B shares was even more dramatic. Those shares closed Wednesday at $6.90, up 221 percent from $2.15 on June 9.

Class A common stock has 1/20 of a vote per share and Class B common stock has one vote per share. 

The company temporarily shut down production of all its own drugs in January and cannot resume production until it meets FDA standards. It is unclear if and when it might get the green light.

It has not been able to file annual results because of an internal probe of a variety of issues  including  regulatory matters and management misconduct. It recently said that when it does file its annual report, that it expects its outside auditing firm to raise questions about its ability to continue as a going concern.

KV has said it anticipates net revenues will be significantly hurt by the production stoppage, recalls of its products, disposal of of inventory and customer claims.