Mortgage lender Impac Mortgage Holdings (IMH) notified the public Monday that the New York Stock Exchange informed the company about "unusual trading activity" in relation to the firm's stock. It didn't offer specifics.

The mortgage company said in a statement that it generally does not comment on market rumors or speculation, and a spokesperson could not be immediately reached for comment.

Impac did not specify why unusual trading would be cited as a concern, but did release a blanket statement about the NYSE MKT concerns.  

Impac's operations include not only mortgage lending activity, but loss mitigation and real estate services for various portfolios.

Impac's stock by the end of the day was trading at $14.21, up 15.25%.  During the previous day's close, the stock was trading at $12.33, before opening at $12.54 on Monday morning.