Palo Alto Networks Inc.’s          PANW,         -0.45%        three-for-one stock split went into effect Tuesday following the cybersecurity company’s announcement during its quarterly earnings report in late August. Shares opened at $183.75 Tuesday and were last down 1% from Monday’s split-adjusted close of $182.96, for a year-to-date of about 2% decline, compared with a 23% fall in the ETFMG Prime Cyber Security ETF          HACK,         -0.15%,        a 17% decline in the S&P 500 index          SPX,         +0.48%,        and a 25% drop in the tech-heavy Nasdaq Composite Index          COMP,         +0.80%.        The split leaves Palo Alto Networks with about 299 million shares outstanding, according to FactSet data.