Shares of GoPro and its supplier Ambarella respectively tumbled 8% and 6% on Monday after Pacific Crest analyst Brad Erickson warned that GoPro’s “inventories are again nearing all-time highs.” Erickson, who based that assertion on channel checks in the U.S., also warns that GoPro’s domestic sell-through of cameras has declined “roughly 40% year-over-year.” Pacific Crest previously estimated that up to 25% of Ambarella’s revenue could come from GoPro in 2016.