One thing you can say about Cathie Wood is that she's persistent. The aggressive growth investor who's also the co-founder, CEO, and ace stock picker at Ark Invest enjoys swinging the fences. She's also not afraid to go for the safe single, binge-buying some of her favorite holdings over and over again. She publishes Ark Invest's transactions at the end of every market day. Something out of the ordinary happened on Friday night, as she announced her purchases from earlier in the day. PagerDuty (PD 0.75%) wa ...