The S&P 500 Index tracks the overall movement of the stock market by considering the stock prices of 500 large corporations. The file Stock Prices,provided in the textbooks web data base, contains weekly data for this index as well as the daily closing stock prices for three companies from January 2, 2008 to January 12, 2009. The following variables are included:
WEEK -Week ending on date given
S&P - Weekly closing value for the S&P 500 Index
IBM - Weekly closing stock price for IBM
GE - Weekly closing stock price for General Electric
AAPL - Weekly closing stock price for Apple
a. Construct a time-series plot for the weekly closing values of the S&P 500 Index, General Electric, IBM, and Apple.
b. Explain any patterns present in the plots.
c. Write a short (100 words or less) summary of your findings.