Where do i find a table listing the shares in the Baby Bell telephone
companies that a shareholder in AT&T would have received at the time
of the AT&T break-up in 1984?

7ivy4,

Pretty confusing stuff!

If you owned 500 shares of AT&T on 31 Dec 1983 (total cost 983.78 -
price per share 1.96760), you would have had (the following trading
day) :

Company          Shares      Price per share  Total Value
US West            50             1.75900        87.95
BellSouth          50             2.66220       133.11
Pacific Telesis    50             1.74720        87.36
Southwestern Bell  50             1.86720        93.36
Ameritech          50             2.03240       101.62
Nynex              50             1.93600        96.80
Bell Atlantic      50             2.06400       103.20

That is only the start of it! According to denvertax.com :

"To get from 12/31/1983 to now there were 36 cost basis adjustments
for spin-offs, split-offs and mergers and 24 cost per share
adjustments for splits"

I actually used denver tax's software to figure this out for you (they
have a free demo) - I'm sure there are legal and regulatory documents
that have the official details, but I only have access to them through
private databases, so I did not search for the original articles.

AT&T Divestiture Basis Tracker:
http://www.denvertax.com/att-tax-basis/Default.htm

AT&T's side of the story:
http://www.att.com/history/

Interesting article on AT&T based stock from thestreet.com:
http://www.thestreet.com/funds/deardagen/802701.html

Google Search options :

"baby bells" shareholder bellsouth "southwestern bell" ameritech nynex