Some 3,000 jobs about 10 percent of the total workforce could be affected, sources close to the company told the newspaper.
The cuts may be in the marketplace division, which includes eBay.com and StubHub, according to WSJ.
An eBay spokeswoman did not confirm or deny the news, and instead said the company is focused on ensuring the success of the new business once the split is complete.
"We are focused on running the business and setting eBay and PayPal up for success as independent companies," Amanda Miller told AFP.
eBay announced in September it was spinning off PayPal in a bid to help the unit compete better in the fast-moving online payments segment.
The plan will take effect next year, and comes after months of pressure led by activist investor Carl Icahn, who had assailed eBay for poor management and claimed that keeping eBay tied with PayPal depressed the value of both.
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