The cause of the spike could not be immediately determined. Mattel jumped up 11 percent, while Hasbro was up nearly 5 percent.
Both companies declined to comment.
The toymakers have been under pressure for years from cheaper off-shore imports, margin-squeezing big-box retailers and children who increasingly prefer tablets to toys. The bankruptcy last year of Toys R Us, one of the world's largest toy retailers, threw a further wrench into the industry. According to Jefferies, the retailer comprised 11 percent, 9 percent and 15 percent of 2016 global sales for Mattel, Hasbro and Jakks Pacific, respectively.
Still, a tie-up might lead to antitrust concerns, which have hindered such deal talks before.