Despite a rising share price, a Morristown, N.J., insurer and its parent are pressing a $6 billion suit alleging that hedge funds depressed its stock price.

The complaint, by Crum & Forster Holdings Corp. and its parent, Fairfax Financial Holdings Limited of Toronto, alleges that S.A.C. Capital Management, a $7 billion hedge fund, and accomplices drove down Fairfax’s stock price so they could profit by short-selling the stock.