According to Wikipedia, In corporate law, a stock certificate (also known as certificate of stock or share certificate) is a legal document that certifies ownership of a specific number of shares of stock in a corporation.
The Stock Exchange that the Courier-Citizen Company used after its public offering in 1972 was NASDAQ. It is the second-largest exchange in the U.S. and world by market capitalization, only behind the New York Stock Exchange. As of 2015, the NASDAQ has had an average annualized growth rate of 9.29% since its opening in February 1971. Since the end of the recession in June 2009 however, it has increased by 18.49% per year.
From the collection of documents from the Courier-Citizen Company, there were numerous books filled with original stock certificates. There were all different kinds, different classes, different colors, and different years and on this page, there is an overview of the individual types of certificates that were in the books. The certificates were utilized to document ownership of shares of Courier-Citizen and were legal proof for dividend payments. Today, a vast majority of companies do not issue paper certificates so the samples shown here illustrate an old era in corporate management. The stock certificates are also unique artifacts and examples of the technical printing expertise and decorative artwork representative of the times.
In addition to selling their own corporate stock, the Courier-Citizen Company also issued shares in other subsidiary companies, including the Middlesex Realty Trust, which was a real estate company from Acton, Massachusetts. 
As part of the archive, the University maintains examples of company ledgers which highlight the owners of stock. This is an example of a page from a 1926 book which shows the date, the name, how many stocks that person owned, as well as the certificate number.
