NEW YORK (AP) — It's been seven years since one of the stock market's best-ever runs began, but the anniversary is passing without a party yet again.

This bull market is the third-longest in history, and investors in mutual funds that track the broad U.S. market have more than tripled their money since a 6 percent jump seven years ago Thursday marked the start of the Standard & Poor's 500 index's run.

Investors still don't believe in it. This bull market has been mistrusted and unloved from the start, even though it has managed to stagger higher amid a government shutdown, a debt crisis in Europe that nearly tore apart the European Union and a growth slowdown in China, the world's economic engine.

At times, even as the market stayed strong, regular investors were pulling money out of stocks instead of investing more as in past bull markets. Now, worries are high that the market has already topped out, and that a recession may be coming to knock the S&P 500 down again.

The index is down about 7 percent from its peak in May, and other investments like oil and emerging-market stocks have crashed in recent months, turning from bull to bear by falling 20 percent in value from recent highs. It's an indication of what a strange bull market this has been, and another reminder of how important it is to stay diversified. Nearly three quarters of retirement savings in 401ks and similar plans is in stocks, according to a survey of plans at Vanguard, one of the largest retirement account administrators.

HOW THIS BULL MEASURES UP

This bull market may soon become the second-longest since World War II.

Yes, stocks have been weak this year, and at one point last month the S&P 500 was down as much as 14 percent from its peak. But the index has so far managed to avoid a drop of 20 percent, the arbitrary line where market watchers say a bull market morphs into a bear market. If that were to happen, traders would say the bull market ended on May 21, when the S&P 500 set its last record high.

If the bull market does manage to stay alive, it would join only two others that made it into an eighth year. One of those, in the 1950s, petered out less than two months after passing the milestone. The other became the longest bull market, extending from late 1990 into 2000, according to S&P Capital IQ.

UNLOVED BULL

This bull market had to overcome the challenges and doubts that haunted the nation after the 2008 financial crisis, which helped wipe out more than 8 million jobs and half of stock investors' holdings.

At first, investors didn't trust the bull because the job market was so slow to recover. Later, in 2011, it was concerns about the still-weak economy combined with worries about political tensions around the world. Fear spiked that the U.S. government could default on its debt and that the European Union could unravel due to its debt crisis. The S&P 500 dropped nearly 20 percent from late April 2011 into early October 2011, coming close to falling into a bear market before recovering.

Even when the stock market was doing well, like in 2013 when the S&P 500 returned 32 percent, investors were slow to embrace the bull. Some thought the market's gains hinged on unprecedented stimulus from the Federal Reserve that could evaporate or lose its power at any moment.

At times money went into U.S. stock mutual funds and exchange-traded funds, but never with the fervor that gripped investors during the dot-com boom or other bull markets. Over the last year, investors withdrew a net $66 billion from U.S. stock funds, even as they invested elsewhere. Just over $205 billion went into foreign stock funds over the same time, and nearly $8 billion entered taxable bond funds.

WHY ALL THIS DISTRUST STILL?

One word: recession. Investors are worried again that the economy, which has been growing only modestly, is about to go into reverse. The same fear has gripped investors repeatedly through the bull market. It started so early in the economic recovery, which began in June 2009, that "double-dip recession" became a common phrase.

The worries now focus on the slowdown in China, which is the world's second-largest economy and for years was its main engine of growth. Economies in Europe and elsewhere are also still growing only modestly, if at all, which pressures U.S. exporters.

And the Federal Reserve has almost no room to cut rates to stimulate the economy because rates are still close to a record low.

All that is against the backdrop of an economic recovery that, like the bull market, is also geriatric at nearly seven years old. The average economic expansion has lasted less than five years, going back to 1945, according to the National Bureau of Economic Research.

YOU SHOULD SEE THE OTHER GUY

Investors may be uninspired by the broad U.S. market, but it has demonstrated its value to investors by holding up better than many other investments in recent months and years.

Oil has lost nearly two thirds of its value over the last two years, a result of a global oversupply. That's dragged down the value of energy companies in the S&P 500 by 30 percent. China's struggles have hurt stock markets across the developing world. Emerging-market stocks have lost 26 percent since a recent peak in April.

Even portions of the U.S. stock market outside the energy industry, like small U.S. company stocks, fell into a bear market, though they have recovered somewhat in recent weeks.

Many strategists on Wall Street say they expect the bull market for the S&P 500 to persevere, even if few expect huge gains. U.S. companies — and the stock market — have so far weathered a lot, strategists from Deutsche Bank wrote in a recent research report.

"In our view, this increases the chances of this being a slow but long expansion that rivals the 10-year record," they said.