I'm new to investing, so I'm hoping someone could clear this up for me. As I understand it, the Dow Jones Industrial Average (DJIA) comprises of 30 major American companies. Let's say, hypothetically speaking, that on January 23rd, 1976 I invested $30,000 ($1,000 each) to all of the companies listed within the DJIA. At the time, the value of the DJIA market index was 953.95. Currently, even as it is plummeting, the DJIA has a value of 15,748.01 which is an increase of approximately 1550%. Assuming that I kept track of my investment and exchanged stock in companies leaving the DJIA for companies joining the DJIA, would my initial investment now have a value of about $495,250 (that same percentage increase)? Or am I missing something?
Assuming that I calculated those numbers correctly, is this gain approximately better, equal to, or worse than an average investment for that timespan?