(AP) — Shares in British-headquartered Dialog Semiconductor plunged on Tuesday after an analyst downgrade that cited uncertainty over the future of its relationship with Apple.

Shares in the firm were down 14.6 percent to 40.80 euros ($43.19) in late trading in Frankfurt, where Dialog Semiconductor is listed.

They regained some ground after earlier dropping as low as 30.60 euros.

The selling followed an analyst note from Bankhaus Lampe that downgraded Dialog to “sell.” It said there appeared to be “strong evidence” that Apple is developing its own power management chip for the iPhone and “intends to replace the chip made by Dialog at least in part.”

Dialog later issued a statement in which it said it “knows of no business reason” for the movement in its share price and that its “business relationships are in line with the normal course of business.”

Last week, shares in British chipmaker Imagination Technologies dived after that company announced that Apple plans to stop using its products.