Nvidia shares are tumbling in premarket trading Wednesday as the firm said it expects to take a $5.5 billion first-quarter charge after the U.S. limited exports of its artificial intelligence chips to China.

Nvidia did not warn at least some major customers in advance about new U.S. export rules it was told about a week ago requiring it to obtain licenses to sell its China-focused artificial intelligence chip,

Nvidia Corp.’s shares were tumbling in after-hours trading Tuesday, after the chip giant disclosed in a regulatory filing that it expects to include charges of up to $5.5 billion in its fiscal first quarter related to licensing of its chips to the Chinese market.