There are several ways to rank America’s most widely followed public companies. They could be ranked by annual sales, brand value, market capitalization, number of customers, or profits. Another approach is to analyze how often the investing public looks up a corporation’s stock symbol. It is hard to determine this exactly.

First, there has to be a time period. A company such as BP plc (NYSE: BP) was widely fo
llowed by investors after the Gulf oil spill. Investor interest has dropped since then. Public corporations that are involved in scandals or legal problems are closely followed for a while. 24/7 Wall St. looked at data which covered a period from three months to one year to average spikes in public interest in a stock.

Another way to determine how often a company’s stock price is looked up is volume. Citigroup trades 550 million shares a day, which makes it the most widely traded public company in America. But, Citi’s shares are only worth $5. Apple trades only 15 million shares a day, but its share price is $340. The corporations that 24/7 Wall St. examined had to have both high share prices and trading volume.

Another piece of data 24/7 Wall St. considered was short interest. It is easier to sell a stock short when the number of shares outstanding and the number of shares traded are large. Short interest in some widely traded companies is more than 100 million shares, which is a sign that the interest in the stock drive both volume and negative short bets against the company’s future value.

Finally, 24/7 Wall St. considered information from several media sources which have stock quote pages. TheStreet.com occasionally posts its most widely looked up stocks. Google has a search feature to show which stocks are widely followed. Stocktwits and other financial social network sites have measurements of those stocks that are most widely followed by their members.

24/7 Wall St. took these data points to create a list of the ten stocks which Americans watch most frequently and follow most closely. Information on short interest, revenue, three-month trading volume, and market capitalization are included.

These are the Ten Public Companies Americans Are Most Interested In:

1. Merck (NYSE: MRK)
> Average Volume (3 Month): 15 Million Shares
> Market Cap: $104.4 Billion
> Shares Short As Of 12/31/10: 21.2 Million Shares
>Annual Sales: $27.5 Billion

Merck is a product of the merger of its core pharma business with competitor Schering-Plough. The transaction was valued at $41 billion and was similar to one which put Pfizer together with Wyeth at about the same time. The reason for these mergers is that the large drug companies have started to lose patents on their largest selling drugs. Merck is a market proxy for the entire drug R&D and marketing industry worldwide which is the reason it is so closely followed by investors.