A spokesman for the company would not confirm the 40 percent figure, but said "operational moves" would continue, the Journal reported Wednesday.
The company would continue with "operational moves ... to ensure we have the right people in the right roles to drive new opportunities in mobile computing," the spokesman said.
The company that was a breakaway leader in the smartphone market under its previous name of Research In Motion has been eclipsed by Apple Inc. and Samsung Electronics over the years.
The company has tried to redefine itself with a name change, lifting the name from the smartphone that pioneered the smartphone market.
The firm currently has around 12,700 employees, the Journal reported.
Two years ago, when the BlackBerry phone made up 14 percent of the market, the company included 17,000 employees. Now the phone accounts for 3 percent of the U.S. market, the Journal said.
In August, the company said it was looking for strategic options, including a possible sale of the company.
Revenue in 2012 alone dropped 40 percent to $11 billion, the Journal said.