HispanicBusiness

For a bull market that arguably has been as despised, distrusted and downright disrespected as any major stock market advance in Wall Street history, the bull that began in March 2009 has put up numbers to rival some of the best bull runs in history.

Since March 9, 2009, the Standard & Poor's 500-stock index has gained as much as 117%. That's the index's seventh-best-performing bull market ever, S&P Capital IQ says. The advance has lasted 1,366 days, the eighth-longest on record, says Bespoke Investment Group. That adds up to 3 years and 9 months -- or nearly 4 years.

That's old when compared with the average lifespan of a bull market, which is 3.8 years, InvesTech Research data going back to 1932 show.

A graying bull, while not a sign of imminent death, is certainly a reason for investors to avoid complacency.

"This aging bull market will be 4 years old in March 2013, (and) the average age of a bull run is 4 years," Mary Ann Bartels, a technical research analyst at Bank of America Merrill Lynch, wrote in a client note.

Since World War II, only six of 11 bull markets have celebrated their 4th birthdays, says S&P Capital IQ. Here's a bright side: Five of those six lived to at least 5 and three were around to blow out the candles on their sixth birthday. What's more, bulls that live beyond their fourth birthday have posted big additional gains: 21%, on average, for those lasting 5 years, and 26% for those that turned 6.