Offer your thoughts or opinion on the input financial query or topic using your financial background.

Should I use regular or adjusted close for backtesting?
A one year period of study - Stock A trades at $100, and doesn't increase in value, but has $10 in dividends over the period.  Stock B starts at $100, no dividend, and ends at $105. However you account for this, it would be incorrect to ignore stock A's 10% return over the period.  To flip to a real example, MoneyChimp shows the S&P return from Jan 1980 to Dec 2012 as +3264% yet, the index only rose from 107.94 to 1426.19 or +1221%.  The error expands with greater time and larger dividends involved, a good analysis won't ignore any dividends or splits.