citadel securities went through the meme stock frenzy with zero seconds of downtime. the reason is a decision they'd made years earlier about a number. peng zhao, their ceo, explains how they arrived at it: "we planned for six times the capacity of the previous market peak. and why was it six times?" step one: "i need enough capacity for the highest amount of volume and message rate i've ever seen." step two: "your next market peak is going to be higher than the previous one. so you double whatever the previous peak was." step three is the interesting one: "then we thought to ourselves, i don't think our competitors are going to spend a tech budget to plan for that kind of market peak. what if they all go down? and if we're 35 to 40% of the market, then triple my capacity yet from there." so: previous peak, doubled for growth, tripled again for everyone else failing. six times. "and we almost had to use all of it." they didn't size their infrastructure for their own worst day. they sized it for everyone else's.