KEY POINTS
  • Investing legend Bob Farrell's 10 rules for investing are still passed around on Wall Street today and ring true for the current bull market.
  • "Markets are strongest when they are broad and weakest when they narrow to a handful if blue-chip names," Rosenberg Research pointed to Farrell's seventh rule in a note to clients Monday.
  • Apple, Google parent Alphabet, Facebook, Microsoft and Amazon make up nearly 20% of the entire S&P 500 market cap, the highest concentration since the dot-com bubble peak in 2000.
Tourists take a picture with the market bull near the New York Stock Exchange in New York City.

For decades investing legend Bob Farrell was a top Wall Street strategist known for predicting changes in overall stock market direction.

Farrell, 88, was the chief stock market analyst and senior investment advisor at Merrill Lynch, where he worked for 45 years. Farrell is well known for his work as a technical analyst, recognizing the importance of data and patterns.