GoPro Inc. shares plunged nearly 20% in extended trading Wednesday after it announced a delay in shipments of its new HERO8 BLACK cameras. In a conference call with analysts late Wednesday, Chief Executive Nick Woodman said a "late-stage production delay" will push back availability of the cameras until the fourth quarter instead of the third quarter as originally planned, resulting in a fall in revenue. The delay prompted GoPro to trim its annual revenue forecast to $1.22 billion to $1.25 billion, down from $1.25 billion to $1.28 billion. It now expects to post an adjusted profit of between 33 cents and 39 cents per share for the second half of the year, compared with its prior forecast of 37 cents to 49 cents. On Tuesday, the Silicon Valley company announced its HERO8 camera series to uniformly positive reviews.