Blackstone Group LP reached a deal to acquire Gates Global Inc. for around $5.4 billion, said people familiar with the matter, after weeks of prolonged negotiations with the auto parts maker.

The deal, which could be announced as soon as Friday, would mark the second-largest private-equity buyout so far this year, after Cerberus Capital Management LP's $9.4 billion agreement to merge its Albertsons supermarket chain with Safeway Inc.

While the parties were recently in the process of inking the deal, it remained possible the timing of the announcement could slip into next week, some of the people said.

The negotiations between Blackstone and Gates's owners, Onex Corp. and the Canada Pension Plan Investment Board, have been ongoing for several weeks. In March, Blackstone and rival buyout firm TPG together bid for the Denver-based auto parts manufacturer.

But TPG eventually decided to pass on the deal amid concerns about being part of a large consortium of buyers in a sizable takeover. Instead, Blackstone is working with a series of other investment partners to complete the takeover.

The buyers are expected to put about $1.6 billion of their own money into the deal--among the largest equity checks in a private-equity buyout in the past several years--and borrow the rest to finance the takeover, some of the people said. The identities of Blackstone's co-investors wasn't learned.

Write to Mike Spector at mike.spector@wsj.com and Dana Cimilluca at dana.cimilluca@wsj.com

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