How can the current/past stock price of company be calculated?
There are numerous ways to calculate the price of a stock all covered in “Investment Security Analysis”
How to Calculate a Stock Price
However, the best answer is know that the stock market is a Bid – Ask process and a stock price is worth what someone is willing to Buy and the other person is willing to Sell it for. When the two persons reach an agreement, the execution of “a trade” occurs. That is what you see scrolling across the bottom of your TV called the “Ticker Tape”. Trade executions of ticker, volume and trade price of the trade. Prices change every split second during the trading day.
HD@25k 74.94 means Home Depot, 25,000 shares traded at $74.94
Also, In general, if the PE ratio (Price/Earnings) of the S&P 500 is above the, many say the stock is over priced. The current PE ratio October 17, 2013 is 19.89.
If you would like to see Historical prices of stocks, use Yahoo Finance Historical prices.
ETFs have risk of loss which the investor must be willing to bear. This is answered for educational reasons and not intended for any recommendations.
Joe Cantu is a regular commentator for Quora on the following topics: Stock Market, Economics, Defined Benefit Pension Plans, Asset Management, Mutual Funds, Investing, and Exchange Traded Funds.