Shares of WolfSpeed Inc. WOLF were plunging over 14% in premarket trading on Thursday.

What Happened: The stock was reacting to a comment by Tesla executive Colin Campbell at the electric vehicle maker’s Investor Day held late on Wednesday. Campbell, who is VP, Powertrain Engineering, at Tesla, said the company’s next-gen drive unit will use 75% less silicon carbide and accept any battery chemistry.

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He also noted that the company’s next drive unit uses a permanent magnet motor, which doesn’t use any rare metals at all.

Wolfspeed, formerly known as Cree, manufactures wide-bandgap semiconductors made with silicon carbide and gallium nitride materials and devices for power and radio-frequency applications.

Price Action: In premarket trading on Thursday, Wolfspeed stock was plummeting 14.29%, to $64.11, according to Benzinga Pro data.