Mattel Inc. fell in late trading after the company said it would pull a bond sale because of “an anonymous whistleblower letter.”

The company “was made aware of an anonymous whistleblower letter” on Aug. 6, according to a filing. The company said it is terminating the sale of senior notes due in 2027 “to provide the company with an opportunity to investigate the matters set for the in the letter.”

The sale had been scheduled to close on Thursday. Mattel daid it plans to refinance bonds that are due in October 2020 before maturity. It didn’t offer any further details about the letter.

The shares fell as much as 11% to US$11.90 in late trading. The stock had gained 34% this year through Thursday’s close, boosted last month as the company signaled it’s making progress in revamping the company and reported quarterly revenue that outpaced expectations.

Junk-rated Mattel has about $3 billion of debt on its books. About US$250 million of that comes due next year. The toymaker had planned to refinance its 2020 obligation with the pulled bond, which had been sold to investors on Aug. 1.