Cephalon falls after rejecting Valeant

Cephalon Inc.'s shares fell slightly in pre-market trading a day after the U.S. drug company formally rejected a hostile takeover bid by Canada's Valeant Pharmaceuticals International .

Cephalon's shares were down 87 cents to $76.50 on the Nasdaq before markets opened, but still significantly higher than Valeant's offer.

The company said Valeant's offer "significantly undervalues" the Pennsylvania-based drug developer in a letter to Valeant chief executive officer Michael Pearson.

The letter, released after the close of markets on Tuesday, said the Cephalon board has concluded that the March 24 offer of $73 (U.S.) per share was "inadequate and not in the best interests of Cephalon's shareholders."

The board also called the timing of the non-binding offer, which values Cephalon at $5.7-billion, "opportunistic."

It said the 30-day average Cephalon share price of $56.74 on which the offer is based, was near the 52-week low for the company's stock.