Blair Gable/Reuters

Nortel Networks, the defunct Canadian telecommunications equipment maker, says it has agreed to sell more than 6,000 patent assets to an alliance made up of Apple, Microsoft and other technology giants for $4.5 billion in cash.

The group of companies, which also includes Research in Motion, Sony, Ericsson and EMC, beat out Google and Intel for the patents and patent applications that Nortel had accumulated when it was still one of the largest telecommunications equipment makers in North America.

Nortel, which filed for bankruptcy in 2009, said in a statement late Thursday that it had sold its last remaining patents, covering businesses including wireless and networking technology and semiconductors, in an auction that it called “very robust.”

“The size and dollar value for this transaction is unprecedented, as was the significant interest in the portfolio among major companies around the world,” said George A. Riedel, chief strategy officer of Nortel.

Nortel delayed the auction once last month because of what it called “significant interest,” and started the sale on Monday. Nortel said it hoped to close the transaction in the third quarter.

In April, Google made a stalking-horse bid of $900 million for the patents, some of which are related to the wireless technology known as long-term evolution. Networks based on that technology, considered crucial to the future of telecommunications, are created to carry large amounts of data like streamed video to mobile devices.

The Google offer was interpreted as a defensive move. The search giant was seeking intellectual property rights to shield itself from lawsuits as it moves deeper into the mobile business with its Android software.

Kent Walker, Google’s general counsel, wrote at the time of the bid that it was supposed to “create a disincentive for others to sue Google.”

“The tech world has recently seen an explosion in patent litigation, often involving low-quality software patents,” Mr. Walker wrote.

Now, thousands of crucial patents will be in the hands of rivals like Apple and Microsoft, both of which have shown themselves to be much more aggressive in patent litigation than Google.

On Friday, Mr. Walker said in an e-mail that the auction’s outcome was “disappointing for anyone who believes that open innovation benefits users and promotes creativity and competition.”

The sale announced Thursday will require approval from courts in Canada and the United States, Nortel said. About 2,600 of the patent assets are American. A joint hearing has been scheduled for July 11.

Nortel, based in Mississauga, Ontario, was once a flagship Canadian company but filed for bankruptcy in 2009 after losing nearly $6 billion in 2008.

Since then, it has sold its wireless equipment business for $1.13 billion to the Swedish company Ericsson, which walked away with $340 million worth of patents from the auction on Thursday. More recently, Ericsson bought Telcordia, an American telecom network equipment maker, for $1.15 billion.

In 2009, Nortel sold another unit dealing with enterprise solutions for $475 million to Avaya, a former AT&T unit that is now owned by private equity and which filed for an initial public offering of stock last month.

RIM, Canada’s most prominent technology company since Nortel collapsed, said in a separate statement that it had paid about $770 million for patents at the auction. The sale of patents raised more than the rest of Nortel’s disposals combined.

The company said it did not anticipate that holders of its common shares or preferred stock would benefit from the bankruptcy process. Creditor protection proceedings “will result in the cancellation of these equity interests,” Nortel said.

Nortel was advised by Lazard.

Nortel’s creditors’ committee, which includes the Bank of New York Mellon and the Pension Benefit Guaranty Corporation, hired Jefferies as its financial adviser for the auction, which saw the patent assets reap five times the stalking-horse bid.