Less than a month after the S&P 500 temporarily slipped into bearish territory, the benchmark stock market index officially fell into a bear market at the closing bell on Monday.  
Year-to-date, the S&P 500, comprised of Apple, Berkshire Hathaway, and Tesla Motors, has tumbled nearly 22 percent. The index now joins the tech-heavy Nasdaq Composite Index in a bear market. The Nasdaq has plummeted more than 31 percent so far this year.  
All eyes will be on the Dow Jones Industrial Average to see if it will be the next domino to fall on the New York Stock Exchange. The Dow Jones, maintaining exposure to American Express and Coca-Cola, has dropped about 17 percent year-to-date.  …