Shares of Sprint shot up more than 70 percent on Tuesday while T-Mobile shares also rose after a federal judge approved their $26 billion deal, defeating a lawsuit by a group of states to block the merger.
The ruling clears the path to combine the nation's third and fourth-largest wireless carriers, creating a new telecom giant, in a deal that already won federal approval - when the carriers agreed to sell some assets to Dish.
In a trial in December, the states - led by California and New York - argued that the deal would reduce competition, leading to higher prices, while T-Mobile and Sprint said the merger would better equip the new company to compete with top players such as Verizon and AT&T, leading to lower prices and faster internet speeds.
The companies have also said that uniting could speed up the rollout of a national 5G network, since the deal would combine their spectrum holdings.
Sprint and T-Mobile said in a statement they would move to finalize the merger, which is still subject to certain closing conditions and possible court proceedings.