By Heather Brown

MINNEAPOLIS (WCCO) — Since March 2009, the stock market has been on a roll. The S&P 500 is up about 250 percent.

So, how long do bull markets last?

After the recession of 2008, the stock market started to rebound March 9, 2009. It was the beginning of bull market that hasn’t yet slowed down.

“A bull market is a long-term trend in the stock market,” says Chuck Hannema, a professor of finance at Bethel University. “We’ll see bull market prices are increasing over some period of time.”

A bull market is commonly defined as a 20-percent rise in the S&P 500 after a 20-percent decline. A bull market ends with another 20-percent decline.

Experts measure bull markets differently, but research from Yardeni Research, Inc., shows there have been 13 bull markets since the end of World War II.

They’ve lasted, on average, four years and 10 months and have had an increase of 150-percent.

The current bull market is the third-longest since World War II. The 1987 to 2000 bull market during the dot-com era lasted 12 years and four months. The 1949 to 1957 post-World War II bull market lasted eight years, one month.

Hannema says a number of things can cause the end of a bull market – from war to recession to political changes.

“When the bull market reaches its peak, it gets fragile and little cracks can come in,” he says. “Then all of the sudden it blows up and those cracks are really related to investor sentiment more than anything else.”

[graphiq id=”6Cl0pk6IUex” title=”S&P 500 (SPX) Value Over Time – Trailing Year” width=”600″ height=”458″ url=”” link=”″ link_text=”FindTheCompany | Graphiq” ]

Heather Brown