In a First, Square Tops $100M in US Sales in One Day

noting that this kind of sales volume ranks it as the 13th largest U.S. retailer by annual sales

Statements like this are very misleading. Square isn't a retailer, it is a payment processor. The real question is how Square compares against other card processors, both terminal POS based and mobile reader based?

Alternatively, how much of the market has Square actually taken, and what is their current growth rate? Without knowing pertinent numbers, Square topping $100m after 5 years of operations could be evidence of a damning failure (I'm not saying it is, but rather that we do not have nearly enough data to know).

Edit: grammar

I wish I were an insider so I could see the breakdown of how longtail their business is.

What was the largest contributing business' amount for the day?

I got an email from Square because I bought chocolate at a coffee shop via square.

For comparison, the market leader, First Data, processes about 50x that. $5B per day. Still, not bad.

Furthermore, First Data owns Clover, the other POS system you've been seeing at your local coffee shop.