How A/D Rating Helps to Identify Price Strength?

At least 70% of all trading in the stock market is done by mutual funds, pension funds and other institutional investors. So any time institutions buy or sell a stock, their activity is manifested by increased trading volume. Volume is the best measure of supply and demand and institutional sponsorship. Therefore, it is a reasonable assumption that any time volume is strong, institutions are involved in the trading in a significant way.