Bloomberg ran a story [1] about a supply chain attack against apple, amazon, and others. It made big headlines, but evidence never emerged. It is now generally believed that the story was false.

No one has found these chips and shown them, and the likes of apple and amazon have issued very direct denials (that would be very clear securities fraud if they were false). Much more direct than statements by corporations usually are.

[1] https://www.bloomberg.com/news/articles/2018-10-04/the-big-h...