While worries about the domestic and global economies loom large, the story on the Street in early 2019 is mostly about growing forward, instead of shrinking back. Firms like Airbnb are signing on more users in more places. Square is building up its revenue and active users. Even historically slow spaces, like B2B payments, are showing some signs of picking up the pace. Because the race goes to the swift in an increasing number of verticals, and consumers are impatient for progress.