A Canadian pension fund has filed to open a shareholder lawsuit against BlackBerry maker Research In Motion ( RIMM) over concerns that the audit committee investigating the company's stock option grant practices may not be truly independent. The IronWorkers Ontario Pension Fund, which owns a position in RIM worth slightly more than $ 1.75 million, filed with the Ontario Superior Court of Justice-Commercial List, seeking permission to start a shareholder derivative action against certain RIM directors. "The company's board of directors intends to review the allegations set forth in the Notice of Application and the related Statement Of Claim and will respond in a manner that it considers to be in the best interests of RIM's shareholders," said RIM in a statement. Shares of RIM closed down 69 cents, or 0.5%, to $127.04. RIM initiated an investigation of its historical stock option grant practices on Sept. 28. In its application, the pension fund has made additional demands with respect to the conduct and scope of RIM's ongoing management-initiated, voluntary review of such practices. RIM and the fund did not elaborate on these. The pension fund has been asking RIM to expand the scope of its investigation into the stock option grant practices and has demanded that the company take legal action against the members of its audit committee for breach of fiduciary duty. The fund sent its first letter to RIM on Oct. 23. Three weeks earlier, two members of RIM's audit committee, Douglas Wright and Kendall Cork, investigating option grants recused themselves after earlier allegations that the committee may not entirely be independent. RIM warned it could face additional lawsuits based upon similar allegations.