I think any analysis of AT&T has to have a big break in 1983 with divesture. So much of the company was changed as was its whole focus that pre and post 1983 are totally separate issues.
Also, the divesture of Lucent and Ayaya (sp?) are a factor as well. Stockholders did not necessarily hold on to those companies. Many stockholders ended up with a fractional odd lot that is a nuisance to keep and they sold it back to the company when they had the chance.
IMHO, in analyzing the long term investment value of a stock, the spinoffs do _not_ count. They're separate companies.
To me, the question would be: After divesture one held $1,000 of AT&T stock. Deduct from that all spinoffs net value (after-sale proceeds) at the time of the spinoff. Determine the value of the stock when AT&T was bought out. That is the answer.
Although the question is of historical interest only at this point because the company no longer exists, even if the name is continuing.
Before the 1960s owning stock was primarily for the wealthy. Then, stockbrokers decided to market small lots of blue chip companies to small investors and everyday people got into the stock market. AT&T was the bluest of the blue chips and was a popular stock.
Changes in the financial market have reverted a bit toward the past where more wealthy people own individual stocks. The market has gotten too complicated to follow by individuals, with too many machinations going on. Individuals are more into mutual funds today. As best I can tell, the cost of buying/selling stock has jumped much faster than inflation. In the 1960s many people held but a single share of AT&T (I was one of them, having received it as a gift). In later years that was discouraged with buy backs (as I accepted, it was foolish cashing a dividend check for 45c every quarter that I had to get my father to co-sign).
I don't know if there are any "blue chip" companies today. The business world seems so violatie, where today a company could be considered rock-solid and tomorrow it's near bankruptcy. In the old days the biggest companies had much more steadiness in the price of their stock. Smaller companies and those in riskier ventures had more violatility. (But there were once solid companies, like the railroads, that fell onto hard times and investors lost out).
An old episode of Dick Van Dyke had the Petrie's investing in a shoe store and getting involved in running it.