A sales slowdown and a weak profit forecast gave cybersecurity investors reason to worry. Zscaler (ZS -17.70%) stock collapsed in morning trading Wednesday, down by 17.8% as of 12:04 p.m. ET, even though the company crushed analysts' forecasts for its fiscal fourth quarter when it reported after the closing bell Tuesday. Analysts had expected the cybersecurity company to report adjusted earnings of $0.69 per share on sales of $567.9 million for the quarter. Instead, its profits were $0.88 per share, and sal ...