Despite vowing to hold firm on its takeover bid for

Chiron

(CHIR) - Get Report

, the Swiss drug giant

Novartis

(NVS) - Get Report

raised its offer to $48 a share from $45 a share.

The bid represents a truce among Chiron, Novartis and dissident shareholders of the target company who said $45 was too low. Chiron said Monday that the opponents support the new price and will vote for the deal.

The new offer came nine days before Chiron shareholders were scheduled to vote on Novartis' effort to acquire

the 56% stake in the company that it doesn't own. Chiron's shareholder meeting has been rescheduled to April 19 from April 12.

Chiron said it has reached an agreement in principle to settle all shareholder lawsuits criticizing the acquisition. The proposed settlement requires court approval. Chiron also announced that the takeover rules had been changed. Now, the deal needs a majority of Chiron's outstanding shares. Previously, it needed a favorable vote by majority of shares not held by Novartis.

Several big holders , who own 17.5% of Chiron's stock and 30% of the shares under the previous voting rules, had opposed the acquisition. The loudest opponents had been

ValueAct Capital

, a San Francisco hedge fund, and

CAM North America LLC

, a New York investment advisory firm.

Opposition to the Novartis offer carried Chiron's stock price above $45 in late January, and it hovered between $45 and $46 until today. The announcement of a higher offer sent Chiron's shares up $2.08, or 4.5%, to $47.89 by midafternoon. Novartis rose 40 cents to $55.84.

This is the second time Novartis raised its offer for Chiron. Novartis originally offered $40 a share, but that was

rejected by Chiron's board in early September as too low.