Klaviyo grew up inside Shopify's world, and Shopify owned a stake in it by the time it went public. The Boston company's software sent online shoppers emails and texts based on what they had looked at or left in their cart. More than 130,000 businesses used it. When Klaviyo listed in September 2023, the IPO market had been closed for most of two years, and its debut came the day after Instacart's.

Data First, Then the Email

Andrew Bialecki and Ed Hallen founded Klaviyo in Boston in 2012. Most email tools sent the same blast to everyone. Their bet was that a store's own customer data should drive every message: a reminder for an abandoned cart, a note when an item came back in stock. Klaviyo connected tightly to Shopify and other store platforms, and it grew for years with little outside money.

A Test for the IPO Window

Klaviyo priced at $30 a share on September 19, 2023, above a range it had already raised, and sold about $576 million of stock. It began trading on the New York Stock Exchange as KVYO the next day. It opened at $36.75 and closed up about 9 percent. Klaviyo still trades on the NYSE as KVYO.

Cover: At the Piano, Anders Zorn. Art Institute of Chicago, public domain. Chosen for a pianist at the keys (one message, tuned to the listener).