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.
When you see that in order to produce, you need to obtain permission from men who produce nothing - when you see that money is flowing to those who deal, not in goods, but in favors - when you see that men get richer by graft and by pull than by work, and your laws don't protect you against them, but protect them against you - when you see corruption being rewarded and honesty becoming a self-sacrifice - you may know that your society is doomed. - Ayn Rand