TORONTO (Reuters) - Shares of Research in Motion Ltd skidded 10 percent at the open on Wednesday after the BlackBerry maker warned on Tuesday it would likely report a shock first-quarter operating loss.

Shares of RIM plunged C$1.20, or 10 percent, to C$10.31 on the Toronto Stock Exchange. The U.S.-listed shares fell 10.8 percent to $10.01.

(Reporting By Jennifer Kwan; Editing by Jeffrey Hodgson)