A rising tide didn’t lift all boats in the chip sector on Friday.

Advanced Micro Devices Inc.’s stock

AMD fell sharply Friday to rank among the S&P 500’s SPX worst performers on the day. The selloff came after Broadcom Inc. AVGO announced that it was adding a fourth customer for its custom artificial-intelligence chips — a sign of continued demand for AI chips, but perhaps not in the way AMD investors may have hoped.