Interesting question.

According to Wikipedia, Standard & Poors was the first to standardize ticker symbols for the ticker machines, but implies that prior to that nonstandard symbols were sent over the tape. Some of those could very well have been abbreviated company names, but the article isn't well-sourced and I haven't found anything better yet.

Will post a followup if I run across anything more. Surely somebody has devoted their life to an authoritative history of the ticker tape, so the info's got to be out there somewhere.

Somewhere buried in this site for vintage ticker machines might be the info you seek - someone is probably out there selling original printed tapes from various generations of machines.