Sabre started as American Airlines' answer to a mess of index cards. The airline and IBM built a computer system around 1960 to track who sat in which seat. By 1996 that system had grown into a business of its own, serving travel agents around the world and running a new website called Travelocity. That October, American's parent AMR sold a slice of Sabre to the public and kept the rest.

A Seat Map in a Mainframe

American Airlines and IBM designed Sabre to replace clerks who tracked bookings by hand. It worked so well that American put Sabre terminals in travel agencies, where agents could book flights on many airlines. Every booking earned a fee. Sabre also ran American's own computer operations from its base in Fort Worth, Texas. By the mid-1990s Sabre was among the largest private computer systems in the world, with terminals in travel agencies on every continent.

Twice Through the Door

Sabre priced its offering at $27 a share in October 1996. AMR kept about 82 percent of the shares and almost all of the votes. In 2000 AMR spun off its remaining stake to its own shareholders. Silver Lake and TPG took Sabre private in 2007, in a deal worth about $5 billion including debt. Sabre came back to the public market in April 2014 and still trades on Nasdaq under the ticker SABR.

Cover: Self-Portrait with Raised Sabre, Rembrandt van Rijn. Art Institute of Chicago, public domain. Chosen for a raised sabre (the company's name).