Judge Sam Glasscock rejected Cooper Tire's allegations that Apollo Tyres was intentionally dragging its feet in talks with the United Steel Workers as an excuse to cut the deal's price.
Cooper Tire had wanted the judge to order Apollo to accept a labour agreement that Cooper had negotiated and then order the buyout deal to close on its original terms. When the two companies announced the deal in June they anticipated it would close by October 4.
"We are pleased that the Delaware court has found that Apollo Tyres is not in breach of its merger agreement with Cooper Tire," said Apollo in a statement. "Apollo Tyres continues to believe in the merits of the combination and is committed to finding a sensible way forward."
Cooper Tire, in a statement late Friday, said it is disappointed with the decision and is evaluating its options while it awaits the court's ruling on other open matters in the case.
Glasscock did not find that Apollo Tyres was suffering from buyer's remorse, as Cooper Tire alleged. He also said he found no evidence the Indian company had negotiated in bad faith with Cooper's unions.
Glasscock ruled following closing arguments on Friday in his Georgetown, Delaware, courtroom, according to court documents. A three-day trial in the dispute ended Thursday.
Cooper Tite shares fell sharply as the judge's ruling reached investors. The shares ended down 11.45 percent at $23.82 on the New York Stock Exchange on Friday.
Apollo Tyres had agreed to buy Cooper for $35 per share.
After Cooper sued, Apollo Tyres made its own allegations and said it was under no obligation to close, in part because Cooper Tires had not provided updated financial information.
As part of his ruling, Glasscock also cleared the way for Cooper Tire to appeal to Delaware's Supreme Court. The state's high court has a reputation for hearing cases quickly. Last month it reversed a ruling in less than three weeks in an $8.2 billion deal involving Vivendi and Activision Blizzard Inc.
The Cooper Tire and Apollo Tyres trial centered around problems in reaching a new labour contract at two Cooper plants, and on Cooper's renegade joint venture partner in China that has locked out managers from the U.S. company.
Hanging in the balance is a deal that would transform Apollo Tyres from a company focused on its domestic market into the seventh-biggest tire maker in the world. Cooper shareholders stand to lose a 40 percent premium for their stock if the deal collapses.
Apollo Tyres has said it wants a lower price that reflects the increased cost of a new labour deal and the unanticipated risks associated with the Chinese lockout.
The case is Cooper Tire & Rubber Co v. Apollo Tyres (Mauritius) Holdings Pvt. Ltd, Delaware Court of Chancery, No. 8980.