The hostilities between two prominent media companies are unlikely to cool off any time soon.
On Wednesday, the CBS Corporation amended its lawsuit against its parent company, intensifying the battle for control of the network being waged between its chief executive officer, Leslie Moonves, and its controlling shareholder, Shari Redstone.
The legal maneuver was the latest in a series of steps taken by CBS to prevent Ms. Redstone, the president of National Amusements, which acquired CBS in 2000, from merging the company with Viacom, its corporate sibling.
CBS amended the lawsuit in the wake of a tense board meeting during which its board voted to dilute Ms. Redstone’s influence over the company. Immediately after the vote, National Amusements called it invalid. In the amended complaint, filed in Delaware Chancery Court, CBS asserted the independence of its board and asked the court to rule on which side’s interpretation of the recent vote is lawful.
The amended suit also accuses Ms. Redstone of trying to “compel” the merger of CBS and Viacom, which it described as “not in the best interests of CBS and its stockholders.” While favoring a merger, Ms. Redstone has maintained that she has no intention of forcing one.
The daughter of the ailing entertainment mogul Sumner M. Redstone, Ms. Redstone has been seeking a merger of CBS and Viacom since 2016. The two companies were one and the same, within the Redstones’ company, between 2000 and 2005, when National Amusements split them apart. In recent months, CBS has resisted a reunification.
On the day before the CBS board was scheduled to meet last week, National Amusements made a sudden and significant change to the CBS bylaws: From now on, the company said, any vote would require a supermajority — 90 percent of the 14 CBS board members — for approval.
The showdown took place last Thursday on the 35th floor of the CBS Building, known as Black Rock, in Midtown Manhattan. Mr. Moonves and Ms. Redstone, onetime allies, were both present as the board voted 11 to 3 to significantly diminish Ms. Redstone’s voting power. But that result fell shy of 90 percent.
Afterward, both sides declared victory, meaning that they are effectively deadlocked.
Was the vote valid? Was National Amusements within its rights to change the CBS bylaws? Or, as the amended lawsuit filed by CBS suggests, should the CBS board operate independently of its main shareholder? These are questions for the Delaware Court chancellor to settle in the weeks or months ahead.
“National Amusements exercised its legal right to amend CBS’s bylaws, and this change was effective immediately,” the company said in a statement. “We are confident the court will uphold National Amusements’ action.”
At stake is whether Mr. Moonves will remain in power at the company where he has held significant sway for two decades.
Viacom, the beleaguered media company that owns Paramount and cable networks like Comedy Central and MTV, has been in search of a turnaround in recent years. CBS, the owner of Showtime, Simon & Schuster and the broadcast network that is home to “60 Minutes” and “Survivor,” has had a run of success since it was split from Viacom in 2005.
The two companies are operating as relatively small shops while many others are trying to bulk up to compete with upstart digital rivals like Netflix and Facebook.
Analysts are divided over what they see as the likely outcome. The firm Bernstein Research said last week that there was a “near-zero chance” that CBS would be forced to merge with Viacom.
“By the way, if there is a company out there who is thinking about making a bid for CBS, now would be the perfect time to do so,” the firm said in a statement to investors. “The stock price is low, and the controlling shareholder would have a particularly hard time rejecting a strong offer.”
The Redstones are the controlling shareholders.