John Peddie Research has released its review of the GPU market for Q4 2018. Overall GPU shipments were down by 2.65% from the previous quarter, with Nvidia shipments decreasing by 7.62%, AMD's by 6.81%, and Intel's GPU shipments falling by 0.67%. However, GPU shipments for notebooks increased as the cryptocurrency crash continued to affect desktop GPU demand.
https://www.notebookcheck.net/Overall-GPU-shipments-down-for-Nvidia-AMD-and-Intel-in-Q4-2018-but-laptop-GPU-shipments-rise.411453.0.html